Check the burner and burner orifice for clogs/spider webs/etc. . make sure all is clear and then see if gas is flowing.
IF gas valve is not opening properly, it cannot be repaired and must be replaced.
IF it is getting power and it is, it should open, if not it is bad.
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?