First thing is don't put yourself down for it. Everyone falls off in fact the best riders fall off dozens of times before they become better. There must have a cause for you to fall off it could be your horse spooked, you lost balance, you lost your stirrup or anything. If you can try and think of what happened and why it happened and how you can resolve the issue. Lets say for example your horse spooked in the corner and caused you to fall. Just take him to the corner, not riding just leading him to show him theres nothing to be afraid of and give him a pat. Treat him every time if it is that issue. In terms of mentally recovering you have to think: what is the point wasting time sitting here being upset about my fall when i could be riding my pony right now having the best ride of my life! Honestly life goes by fast and its okay to feel like that but your pony is probably confused as to where you are too. Just take it nice and slow walk around with him and when you feel the times right go further. Hope this helps x
You need to take your time and go slow.
Start to ride with a cool and calm horse that you trust. Ask your monitor to be around (he can lunge you, you will only be focused on your position and your feelings and feel reassured) and be understanding.
You can also ride and hold the mane or even use a garland to be fixed at the beginning.
Really take your time, this is the most important, try to enjoy every moments on your horse and appreciate every victory you make, you can be proud of yourself just by riding again.
Don't forget that you ride for pleasure and not by fear, focus on what you like and your fear will disappear in time :)