1987 Ford Bronco truck wont turn over

Ijust baught a 1987 ford bronco and the guy that I baught it from tells me he just replaced the ignition and the cylinoid and the starter. When I baught it it ran great now its only been a week in half and the ignition wont turn the truck over. I took it to the store one day and then home and when I got back in the truck not even 10 minutes later it wouldnt start. I thought it was the cylinoid so I replaced it again and still nothing. But I can bridge the cylinoid to start the truck. Please give me a better idea of what could be wrong