Not sure I am reading your question correctly and the 1st answer. If the problem is with opening the file with Access (File, Open, ...), you should be able to browse to wherever the file was moved to and open from there. If you are doing File, , you will get an error as the file is no longer there (get same/similar with Word and Excell).
If you are accessing the file from an application (accross a network or some, you will need to change the access string to be whatever / wherever the file is now located. If you want to get the long name back, you can find the file by doing a Win Explorer search (or DIR \*.* /s from DOS). I think the DOS File name is the first few characters + some ~ and such + a number. You can get probalby the exact name by creating a new database with the same long file name in another directory then looking at the DOS file name (forget how to do that, Win Explorer setting, DOS /? may give you switch) may be a different ending Number.