I had that happen with both my 06 and 08 at the exact same time. We went to dinner at a restaurant when we both exited the vehicles we could not lock either one while standing next to them, but worked fine when we got home.

 

I don't know if this will help your issue, but both key remote fobs for my 2007 H3 broke at the hole where the key ring goes through. I ordered two new ones off Ebay for $10 each.

Instead of paying the stealership to program, I popped open the new ones and removed everything - the rubber, the chip, and the battery. I opened my old ones and put the old rubber, old chip, and old battery into the new shell.

Much to my delight, they worked perfectly, and I avoided having to pay $25 to $50 each to have them "programmed". They pop open pretty easy - you can just use a penny on the bottom slot (below the ring hole) to pop them open.

Hope this helps.

 

Did you have a low battery in your h3 or have to boost it or have your battery disconnected? I've had my fobs stop working due to low truck battery. All it took was driving it for a couple of days for it to relearn everything. No reprogramming needed just time. As for the key not working maybe the key lock is seized up from not being used.