How do you guys organize all the daily tiny fires that come up?

Looking for a free software solution or other solution for this. I have my main projects I work on that are easy enough to track. But I constantly have people coming in my office asking for little things here and there. But it's constant. I try to write it all down but then sometimes the paper I wrote it on ends up in the garbage. How do you guys organize all your tasks? I'm forgetting things when people bring me 50 problems a day. I need to track every time someone brings me a task and when I will or am working on it. Any suggestions? I really need to improve my organization as I have epilepsy so my short term memory is nonexistent.