Can a landlord deduct a broken window from security deposit?

We rented a house in the country with a 6 month lease. We moved out over 30 days ago now and have not received our security deposit back yet or an itemized list of deductions. Here is Wisconsin the landlord has 21 days to either return the security deposit in full or give a list of deductions. We are going to be taking them to small claims court. We video taped the house when we moved out to show how clean it was. The only thing that ever happened was in the middle of the night about a month before we moved out, there was a bad storm. The storm produced high winds and blew our large porch swing across the deck and broke one of the living room windows. This was not a fault of ours, but was an act of nature. I just want to know if they can try to charge us for that window...

This was your swing that broke the window? Why didn't you secure that swing by hanging it up high before the storm? (Simply move the swing up by hooking the chain near the top.) Although the storm blew the swing, if your swing hadn't been there, the window would not have been broken. Your LL may have a case for charging you for the window due to your negligence to secure your belongings before a storm. If you failed to lower your patio umbrella before a storm and the wind blew it into the neighbor's window, you would be responsible for that, wouldn't you? Same for failing to secure your swing.

Have you written a demand letter to the LL asking for your deposit back first before filing in court? A court may want to see proof that you asked for it and that you submitted a forwarding address to him. Send him a letter, give him your forwarding, and send it by cewrtified mail. Ask that he contact you within 10 days to reply. If he doesn't, then file.