The thermostat is off and the blower won't stop running. I put in a new thermostat but that didn't stop it . I also unpluged the limit switch ans its still blowing. Is there anyone that can help me please?

Typically the blower relay is fused.

Possibly a thermostat. Check to see if it happens in AC mode.
If it does, you can likely eliminate the stat.

What brand/model#? Most modern furnaces are equipped with an electronic control system that will run the circulating blower continuously if a limit switch has tripped open. Look for a diagnostic LED that may be flashing - it could provide some clues.