Did I need to change my cars fuel injector nozziles

My 1992 model ford laser gl 1.3l is having a problem with fuel injection I had taken car to severel garages in my locality but they didnt find the compliant. Some of the mechanics said that its injecter has been dead and it cannot repair and he said I have to change it. My car has been running in LPG for more than 2 years, I never run it in petrol on those years. Now the car is not running in petrol, please help me to solve this.