If i restored my iphone, is there a way to revert to a previously saved version?

I had a problem with my phone and the people at the apple store told me I had to restore my phone to a new version - I knew I'd lose my notes and pictures but wasn't aware I'd lose my contacts and calendar (no, i wasn't using icloud and didn't have them synced anywhere else). THe restore didn't fix the problem… So is there any way for me to "undo" the restore? Maybe restore from like a week ago's version?

I'm afraid you can't restore the previously version. But you can try to restore the contacts. I suggest you to use the iPhone Backup Restore, If you have ever backed up your iPhone data on iTunes ( only one time is also ok), the iPhone Backup Restore will detect all backup files from iTunes. Anyway, free to download it and free to try. The download page is
http://www.iphonebackuprestore.com/
Download& install& run
After running, the iPhone Backup Restore will load all iTunes backup files info, just wait.
A few seconds later, all backed up info will list on the main window. Just click the number to restore iPhone backup info.
Hope it helped.