Short answer: Close lid(screen), remove battery, open lid(screen) and it should work now. Close lid partially to replace battery. If it doesn't work the first time, leave the battery out for 3 minutes, replace and then open lid.
Long answer: I was having trouble with my 2001 Mercury Sable air conditioner blend door (stuck on hot air). I had it replaced several times and a dealer even sold me on replacing the computer unit. So several thousand dollars later I decided to replace the blend door myself when it went out again. I bought the door actuator for about $35 and went to the net to find out where to put it and how to do it and I found a tip from someone else with the same problem. He said to remove the negative battery cable for 3 minutes and replace it. Well it worked and I have done it several times since and it keeps fixing the problem.
I had been having the touchpad quit on my Toshiba laptop since it was new. I carried a USB mouse with me everywhere just in case. So the next time I lost the touchpad I tried the battery solution and wow! After years of trying every software solution I could find, here was a simple solution. I hope it will work for you too. It sure doesn't cost much and doesn't take much time to try it either.