lost my contacts on iphone 4s and itunes doesnt let me restore

Hi!

I just plugged my iphone 4s to my computer to charge it and when i started using it i found out i had no contacts.

When i tried to restore it from my backup on itunes the program says it cant be done because my iphone does not have enough memory to do it, but my available memory is 5gb.

Please help!!

Thanks in advance!!