It could just be a stretched cable.
If you can get behind the lever under the dash, you may be able to grab the cable end with a pair of pliers and pull it open.
Failing that you'll probably need a hoist and you may need to remove the bumper.
You should then be able to reach up to the latch or cable and open it. Then work out why you can't open it with the lever.
There is a small amount of adjustment at the catch if it's simply cable stretch.