rover414 non start?

Our rover 414 (p reg) wont start, When we got it the ady said to just press the right hand button when in the car and it would start. this was fine for a few days but now it wont start, it just beeps and even after replacing the battery in the keyfob it still wont go. we have.We had to disconnect the horns (behind the lower grills) It was only a cheap car but has long MOT and TAX so we want to keep it as we are skint. Oh and when we repklaced the keyfob battery it worked on the remote locking for a day or so. not fussed about all that . infact even if it did not lock we would not mind as long as we can get it to start, Thanks Marty414