It started a month ago when it would barely go forward. Now when I press down on the lever it doesn't move at all. Any suggestions as to what the problem is and how to fix it?

Hi,
You gave no model info, but first I would check to see if the drive belt is healthy and tensioning properly. If that looks good, check the drive disc.
Peace,
Clarke
PS I can look up most any brand when model numbers are supplied.