I see a pattern. I wouldn't allow him to blame the computer. It is his job to save it to the computer. You might want to show him how to save it to DropBox and a flash drive so this doesn't happen. This includes saving his work first and then just pressing save every five minutes or so. Yeah, I know--I don't believe him either. It isn't your responsibility and no one in life will handle that excuse. Once, I lost my lesson plans by not saving them correctly. I retyped them all again. I made sure it never happened again.
As far as you losing work. When I taught junior high, I would collect their work and check right away to see who didn't hand it in. I then let the students know who didn't have it. Don't give him a chance to use the excuse "you lost it". You might say that you will do something special for him. He can directly hand in his work to you if he is concerned about you losing it. He probably won't take you up on your offer, and even if he did, it is such a small inconvenience compared to fighting with him each day.
If students turn their work in on time, I won't lose it. If a single paper gets lost, it means I've lost the entire class'. I take the assignments, clip them and place them in a folder. Unless that entire folder gets gone, I haven't lost a student's. In all of my years teaching I've never lost a *single student's assignment because of this. I have lost the folder once. The exception is if they do not turn it in on time. If their things are separate from the class pile, they might get lost on my desk. So I have students place late work in a special place. If they put it on my counter or my desk, it might get lost. Sometimes students come up a week later and claim that they turned something in the next day. If they didn't hand it to me, it could be mixed in with other papers on the desk. If I didn't come across it, they just don't get credit. You can't just sneak a late paper onto a teacher's counter full of other papers and expect it to get graded.
The computer eating the assignment is not my problem either. If the student is getting upset about this, I think a conversation with Mom and his other teachers might be in order.
1. The student did not put his name on his work. I keep all the no-name papers in a folder at my desk, so we can check that if he believes he has turned it in but didn't receive credit for it.
2. The student is lying. If I see a pattern or start to hear the excuse frequently from the same student(s), I simply tell them that they will need to redo the work. I don't argue about it, and if they start to argue about it I just repeat myself. If this is a very big problem, or if the parent gets involved and starts to raise a fuss, then I will require that the student turn in all work by placing it in a special folder on my desk. The folder has the student's name on the front (one folder per student) and a paper inside where the student writes the date, a description of the assignment, and his initials. I will initial it, too, so that we both know that the assignment was turned in when it should have been turned in. I have only had to do this with one student. Miraculously, all his claims that I've lost his papers have vanished! Shock! Awe!
3. I have actually lost the student's work. I don't believe that this happens as frequently as students claim, but it wouldn't be fair for me to say that it has never happened in the course of my career. My response is either to excuse the assignment (if I'm reasonably certain that the student did the work or if the student has never had any problems like this before) or, as unfair as it may seem, to ask the student to redo the assignment.
Any technology problem is the fault and responsibility of the student. I've seen them all over the years:
"Computer didn't save my file." No, you didn't save your file. Do it again.
"I swear I sent you scans of my homework through Edmodo, but Edmodo sent you this blank Word document instead." No, you sent me the blank document instead of your scans. Do it again.
"I swear the file is on my flash drive." No, it isn't. Do it again.
Easy-peasy. Either it's in the no-name pile or they didn't hand it in. End of discussion. Work is clipped together as I collect it, stacked on my desk, graded at my desk, put into the pass-back trays behind my desk, and handed back.
I can usually find "lost" files on the computer for them. If it isn't there, they redo it.
When a student tries this with me, I tell them to look in the appropriate basket for their hour. That is where all ungraded material is. If I have taken a pile to work on, I will let them look at it. If they don't find it, I tell them that they must not have turned it in. End of story. I don't take things home to grade because I am concerned that they may get lost. They need to figure out where they left the work.
I always reassure students that there are only two places where their papers can possibly go--in my in basket, or in the corrected folder. There's no way for me to lose their papers. If they don't have a major assignment when I collect it, I have them sign their names in a log as well as write the reason why the assignment was not turned in. This year, I have definitely become a fan of Google Docs. I ask students to just share their files with me, and then I can see their progress as their working on their assignments as well as the revision history of the documents.
This has to be an especially tricky issue for those who take paper assignments home with you. How do you assure things stay organized? When I was student teaching, my CT had a color of the rainbow for each class, ROYGBV (no indigo) in order of when we saw them. For example, 2nd period was Red, so their assignments went in the red bin and were then moved to the red folder she gave me for grading. All the folders were bound together with a big spiral. I never lost a paper that way.