Ok if you have a current lease, even if you haven't made a payment for this month, the landlord can't just lock the doors. You have the right to sell your equipment unless you have given it to the landlord in writing.
So at this point, I would immediately send a letter to the landlord by certified mail, so you have proof, stating that you demand entry within 24 hours of their receipt of the letter. It's important to get everything in writing from now going forward in case you end up in court.
The next step is you could try the police, and show them your lease, but they sometimes don't get involved saying it is a civil matter. I tend to disagree. I think if you get locked out of your property by the landlord the police should let you in.
Another option is to have a locksmith open the door for you, again have the lease on you to show him. Then just go in and get all your equipment and leave.
Of course you can go to court, but that isn't going to be as quick, so I would consider that only if your other options are gone.
You may also try just showing up at the attorney's office and insisting on access. You don't deserve for them to treat you this way and you need to be firm (but calm) and direct with them. Insist on access.
Let me know if you have any questions. If not, best of luck.