hi problem with iphone 3gs

hi everyone:

my problem is simple i got an iphone 3gs and it came with ios 5 and it said it was recomended to install ios 6 i did it and it didn t recognized the sim card after a sucesseful instalation and then it said i had to update itunes i did it and then it didn t recognized the device i then it restore and it doesn t it says error it can t restore and now it doesn t pass the hook up to itunes part and it doesn t do anything

pleaes help

i dreamed about iphone and geting one and i bought it on a local ebay

the is supost to be unlocked

help

thanks