Ah, it may be dead. I've lost a few to messing around with partitions.
Boot back into linux, not running from the usb stick. Check which it is using sudo blkid or an equivalent, you probably want /dev/sdb1 but it depends what else is in your system. Or load gparted, that'll tell you.
Open a root terminal
dd if=/dev/zero of=/dev/sdX bs=4k conv=sync,noerror
It'll write zeros all over the entire drive. X must match your system, and you don't want /dev/sdX# but /dev/sdX. Your data is well gone by this point btw. Now open gparted, and after it finishes scanning you should see a 4gb unallocated space in which to make your partition.
You can append bs=512k,count=1 to the command above if you like, but I think its best to be thorough
If staying with windows, I don't know any way to do something equivalent. Any form of unix is likely to have dd available, even osx might do
Good luck
