Power window

Buick century, 2001, custom, 75324 miles, i'm just a girl duh! I know it's a 6 cyl. My drivers window started out by not going down more than 3in when I just touched the button and let go. It used to go all the way up or down. Then the drivers side back window started not working when the car got summer hot inside. Once I ran the ac and cooled it down inside it works. Now I went out and the drivers window was slid about 4 in down overnight. The button will not work to go up but it will work to go down. What is the problem?