If you work in a large commerical company or university, and save files to a network drive, it is quite possible the IT staff will be able to recover the data from a backup tape.
There are several tools available on the Windows platform which might be able to recover your files. But I would advise you to switch off the computer, don't save anything. Then using another computer, search and try to find some software to recover your files.
Essentially in Windows, when you "delete" a file, the OS knows it can write to that part of the disk, but might not have done so. Unless the data has been overwritten, then you have some hope of getting it back. It's more difficult on a Unix platform to recover files - at least that has been my experience.
I don't suppose this will be much consolation, but if you have lost your files you spent 3 months working on, I expect it will take you far less than 3 months to get back to the same position. You will have no doubt done a lot of things in the 3 months which you know led nowhere, so you wont repeat them.
I don't know about you, but I often save my files with a different name. So my "yagi" file will be saved as "yagi" then "yagi2", then "yagi3" etc. So if I screw up, I can go back to an earlier version. Of course that does not help in the event of hardware failure. For that, you have to rely on mirrored disks, and then backups. But saving the files regularly with different names is worth doing.
As tallface65 says, emailing yourself files is useful. .hfss files are not huge, and you can store a lot of them on a gmail or similar acount.