Every Winter I have one stubborn lock on my house that will not allow my key to enter it. A solution that you might carry in your purse or car is hand sanitizer gel! Squirt some on your key and rub it around. Don’t force your key in the lock, rather pump it in slowly. Try turning the key gently and repeat until it works. It should work because almost all hand sanitizers are 60% or more alcohol which is the same ingredient as commercial de-icers. To keep your lock in working order, once you are able to enter your house, spray some WD-40 in it to keep it from re-freezing.