Battery dies/won't hold charge 98ford explorer?

Last night my battery light came on for no apparent reason while i was driving and then my power steering stopped working. Also today driving home the battery light was still on, it stayed near the bottom of the gauge and it completly died, my radio went off after crackling for a short time then my ABS light came on and my power steering still wasnt working. When i got home i shut the car off and it would not start again until i jumped it but the battery wont charge back up. The belt feels loose so I was thinking it might be that but im unsure.. please help!