Zipper is kaput

I bought a coat as a gift last year and, to my disappointment, the zipper seems to be broken. It can be zipped up but then it will come undone from the bottom. I don’t know if it can be repaired but it can, hopefully, be replaced. It might be tricky coordinating this cause on a day like today, the coat is needed if the zipper works or not! Brrrr! I’m sure we can figure something out after this cold snap snaps! If anyone is up to the task, let me know! Thank you in advance!