How To Unlock 'Key' Locks?

I had some process in which ... I need to do some transaction control within dynamic SQL like as follows

Begin tran

insert.......

if @@error <>0

rollback
else

commit

Now, when i executed above dynamic SQL for some cases I think there is a some severe error at insert statement and thus resulted in abnormal termination of Dynamic SQL i.e. neither rollback nor commit is executed.

Now certain row level locks are still present on object involved in insert. Now my question is how should i Unlock those locked resources.

Thanks,

Mandip