If you only got one check valve down the well and it's stuck open from debris(steel well casing or sand coming into the well). You can drop a heavy rod on top of that check valve inside your drop pipe to free it back up and you will need to fix the problem before it happens again. I find the problem can be from your steel casing rotting out from heavy concentrate bleach water being used without clean things off with clean water up top(that brass pitless adapter will let me know or it's your water quality rotting things out).

Like I said before "one check valve has already been tested long ago".