- Can you re-open the file thru Access?
If so then the file association between Access and the file-extention (*.mdb, *.addb, etc... depending on version) has been lost/corrupted.
- If you can not re-open the file within Access after you close it then something has corrupted the file.
- If you can re-open the file within Access on your PC and then the teacher can not open the file either directly or thru the program on the teacher's PC then something is corrupting the file between your PC and the teachers. This can happen in various ways and beyond what I can help you with within this forum.
- As for your Prof/Teacher giving you a failing grade because the file can not be opened by that individual, that is tad out of the scope of the site. However, from personal experience, you need to go have a heart-to-heart and take a few print outs of the work you are doing - do a printscreen and waste a few sheets of paper if have to - just have some proof that you're trying to complete the assignment! Having been a teaching assistant (many moons ago) I was usually very forgiving of computer issues beyond my student's abilities to fix ---> provided they could show me some work! I suspect your teacher is the same way, talk with your teacher and get something worked out.