I tried to sync my contacts in my phone (Android 4.0.3), and as a result all my contacts in my phone were changed to the old contacts I had in my google accont on the web. For example. if I had changed a phone number to a new one in my cellular phone before the sync, it changed back to the old number that was on the web. Can I restore the up-to-date numbers that I lost? What could have gone wrong?
I remember having gone through the same problem years back (on a froyo device). Not sure what caused it, but I fixed it as follows:
After doing this two way sync worked perfectly for me. I can not guarantee that this will work for you, but it may be worth a try. Also, make very sure that the export in (1) is complete (check the contents of the file) - also, export to various file formats for safety.
Unfortunately, the changes you made on the phone will have been overwritten and I do not know of a way to revert that. In the future, if the problem persists, you can disable the sync and do it manually using files - it sucks, but at least you won't lose information.