Where has my iTunes library gone

After the last iTunes update to iTunes9, my old iTunes library has disappeared, when my iPod is plugged in, it says that my iPod is sycned with another iTunes library, but I haven't changed laptops or anything, just downloaded the update. Can anyone help please, there are several iPods synced with the old library as we have used homeshare and now the new iTunes version does not recognise any of them. HELP PLEASE