Macbook Pro Screen and Trackpad Problems

I've been having some issues with my Macbook Pro's screen and trackpad. First of i will start by stating my Macbook details such as it is a 13-inch, Mid-2012, has a 2.4 GHz Intel Core i5 processor, has 4GB 1600 MHz DDR3 Memory, and is running with version 10.10.4, OS X Yosemite. My problem is that my screen use to keep freezing, with my initial thought that the thing causing this was that my screen was loose and wobbled at the bottom. Notice how i said that it use to keep freezing, well i used the following links to open it up and tighten it. http://schock.net/articles/2012/02/20/how-to-fix-a-wobbly-macbook-pro-screen/, and https://www.ifixit.com/Guide/MacBook+Pro+13-Inch+Unibody+Early+2011+Display+Repl acement/5140. After this i went on my macbook to see if it was ok, i gently pulled the screen to see if it was wobbly, and to see if it would freeze; fortunately it did not, although some time later while i was using my mac, it randomly froze, which was the last time it had froze (a couple of days ago). One night my macbook suddenly turned off, had a black screen, and kept beeping 3 beeps at a time (before tightening screen). I researched that this could have something to do with my ram, and while i was going to tighten my screen, i first tried swapping the slots of the rams. I also ran the test where you start your mac holding the option+D, but it said that everything was fine. The problem i have with my track pad is that one night, my mouse started to spaz, (without me even touching it) and with how you would swipe the screen so it would go to a different desktop, it stopped halfway and my screen froze (this was before i tightened my screen). I then (using an external mouse, afraid that it would happen again) went into system preferences and chose that the trackpad would be disabled when i plugged in my mouse. When i unplugged it to test out the trackpad, it wouldn't work in the middle. I also think that there might be other problems with my mac as before this all happened, my mac suddenly one night crashed and when i started it, it showed a folder with a question mark. I researched that this was because i had no drive to boot it up on, so i reinstalled OS X, and after this i think it happened again (not sure as it happened months ago ;O). I don't know if this would help, but I installed Windows using Boot Camp, and later uninstalled it. Could Someone please help me out and i would very much appreciate you reading through all of this. 🙂