Bike pedal stop front wheel from turning
We know nothing about bicycle other than how to ride it. We bought a used 26" bike. I hurt my leg and cannot test the bike and I was stupid to trust the seller because he was ridding it towards me. That gave me the impression that it is in working condition. When I am home, I found out that the cranking pedal is stopping the front wheel from turning when it is parallel to the ground. If I had tested it, I definitely detected the problem right away. But it is too late now. I think the bike may be a scam by putting different parts together. BTW, all the parts looks good. I am trying the get some suggestions on how can I get it to work again. I can think of 3 options.
1. Replace the crank arm with a shorter one.
2. Replace the front wheel with a smaller wheels (not sure what's the impact by having difference size front and back wheel)
3. Replace the frame with a bigger frame.
I am not a bike mechanic. But I am handy and have some tools at home. Can anyone suggest what is the easiest way to fix the problem.