(Dex) Attempting an Open Lock check without a set of thieves’ tools imposes a -2 circumstance penalty on the check, even if a simple tool is employed. If you use masterwork thieves’ tools, you gain a +2 circumstance bonus on the check.
The DC for opening a lock varies from 20 to 40, depending on the quality of the lock, as given on the table below.
Opening a lock is a full-round action.
If you have the Nimble Fingers feat, you get a +2 bonus on Open Lock checks.
You cannot pick locks untrained, but you might successfully force them open.