my sin is locked nd i cant use no other sim

See these circumstances:

Unlock 1 = SIM not supported:-> How to unlock your iPhone for use with a different carrier - Apple Support

Unlock 2 = SIM PIN:->  Contact your carrier asking them for your SIM PUK code

If you mean something different, please better specify your needs.

Regards

Giulio

Only the carrier the device is locked to can unlock it for use on other networks.