Lost my library (only on pc)

hello. i need some help please.

itunes asked me to change store to other country store in order to acces something, did it, said that it's unavailable in my country (like doooh, dont know why would it ask me to change the store if it's unavailable), changed back to default store. And tadaaaaaa no more music in library on pc, just on my phone.

how do i get back my library on pc?

thanks