A lot of people say to use hair dryers but it's a dangerous idea because even if a little speck of water gets inside something electric, it's an accident waiting to happen.
We just defrosted our upright freezer because the three year accumulation of ice was so bad, we couldn't get stuff in and out of the shelves anymore.
Different online friends advised me different ways ...
In the wintertime, you could stick your stuff in bags and boxes and leave them outside and your freezer could defrost naturally overnight.
Of course, you didn't plan on defrosting, so that wouldn't help you, and anyway, it's a hundred degrees today !!!
For the summertime, I took laundry hampers or moving type boxes lined with old towels and packed them full lof frozen foods. You can buy ice, too, if you're concerned about stuff defrosting and you getting sick from that. Some stuff stuff can go in the fridge and be OK. (Not ice cream, though.)
Even with three years of ice, it only took us about 2 hours to let everything melt. I kept the door open and the AC off.
My last tip is that I use the lock feature on our big freezer. It's not to keep people out anymore; we're all over 20 years old now. It's to make sure that the freezer stays closed. If you have that feature or can install it, I suggest it. It helps a LOT.