Old landlord won’t give back deposit

He’s probably mad because the old place developed a mold problem and he blames us because I closed ONE of the air vents in the bedroom for a short period of time but mold started in the living room next to the ceiling where there was what looked like a leak but the roof guys never found a leak. The ceiling was wet tho and that’s not our fault HAS nothing to do with an air vent so makes no sense but the roof guys say I closed the vent and said that can cause mold but mold started in living room so makes no sense. Also he was mad because my husband put his dryer outside and he forgot that HE TOLD MY HUSBAND to put the dryer out since it wasn’t working. Guess he’s mad it got wet but it was broken anyways. Anyways he said to send him the new address and he will mail the deposit to the new place. He said that was in the lease about deposit. My husband sent our address and no deposit came in the mail. He’s not picking up the phone or returning phone calls or anything. What can we do? I’m worried that he has our new address so he won’t do anything.