itunes restore button disabled

I took a backup on itunes 10.3 (I am not sure of this version !!) of my iphone 4 which was running on ios4 on my desktop computer. I then upgraded my ios4 to ios5 using itunes on my laptop as my desktop broke down. when i fixed my desktop i hooked up my iphone to the desktop restore from my back up but i got a message that I have to upgrade my itunes to 10.5.. which i did. After the update was complete I hooked my phone and surprisingly itunes did not ask me whether I need to restore and instead it created a new name for the device . The update and restore buttons were disabled and the backup process started automatically. I cancelled the backup with a fear that it might overwrite the original back up file and stopped the whole process.

All my Music library and playlists is available.

I see an old back up in preferences (against my phone with earlier name) and a new back up with the new name given by itunes.

I would like to restore the old back up. is there a way?? I tried right clicking on the device in the left pane but it gives an option to back up and not Restore??

Willl changing the name of the device to the old name help??

Any help is appreciated.

Regards

JB