If you had received message from iTunes like this,
“iTunes has detected an iPod in recovery mode. you must restore this iPod before it can be used with iTunes” ,
you musn’t click restore button. If you did it, then iTunes will do a complete re-sync.
It just only because your operating system detected iPod and put it with drive letter that have been used before. iPod seems to take a drive letter closest to your fixed volumes. For an example, my hard disk drive letter are C, D, and E. I have network drive that assign to letter F. When I plug iPod, automatically, my computer assign drive F to iPod and then i open iTunes, it telling me that “iTunes has detected an iPod in recovery mode”
So the solution is change the drive letter from
Start | Control Panel | Administrative Tools | Computer Management
Start | Run | compmgmt.msc
or right click My Computer then choose Manage…
then click Disk Management and change the iPod drive letter to another letter that not used by other devices or network drives; change drive letter to another available letter, (G, H, I, J, ….Z).