Had problem with laptop so reinstalled it now itunes will not sync on both laptops, it did before.

Question

Had problem with laptop so reinstalled it now itunes will not sync on both laptops, it did before to my iphone5 says cannot sync to 2 libraries until I reinstalled it did.

Answer 1

iDevices can only be synched with one library.  However, you can sync successfully with more than one computer if each has a copy of the same logical library - the identifier that iTunes uses to determine which library is synced an iDevice is recorded within the iTunes database (the iTunes Library.itl file).  The best approach is to replicate your complete library (database, media, artwork, associated files) from one PC to the other.  When you reinstalled iTunes on your laptop it will, by default, have created a new library with a distinct id from that of your other machine.  Even if you copied all your media from one to the other, iTunes will still see the libraries as distinct with respect to syncing iDevices.
If you have configured iTunes to organize your media and to copy files to the iTunes Media folder, then the complete library will be contained within (by default) C:\Users\username\Music\iTunes, with a structure of subfolders and key files like this:
If this is the case, you can (with iTunes not running on either machine):
Copy this iTunes folder from laptop 2 to laptop 1 (the one that's had iTunes reinstalled) - depending on the size of your library you can do this over a network, using a thumb drive, or an external (USB) hard driveNote this this assumes no media on laptop 1 that's not also on laptop 2 - if this isn't the case, there's a slightly different process to follow to ensure that this media is preserved and can be added to the "common" library
Once the copy is complete, make sure that iTunes is using the correct library database by holding down SHIFT as you start iTunes.  When you see this prompt:
select Choose Library..., navigate to the iTunes folder you just copied, select the iTunes Library.itl file you'll find there, and click Open.
For future reference, you can use turingtest2's user tip on Backup your iTunes for Windows library with SyncToy for a suitable method to backup your library to an external drive - you can then, with care, use this to keep the copies of your common library in sync across your laptops.