I was driving on the freeway and something felt weird as I exited. I came to a stop then my front right tire makes a grinding sound then I pull to the side and the right wheel locks up. I can reverse the car and drive forward a few feet until it won’t move, what could have happened?
also if I don’t turn the engine on, it’s able to coast freely in neutral

 

any check engine lights? i assume it's the rear right wheel?
my first instinct is that the brake calipers are locking up or there is a problem in the diff.

what's your mileage?

 

no lights, I’m at 226,000 miles. It’s the passenger side front wheel, maybe the caliper. Before that I noticed the brakes squealing in the morning and then occasionally when I brake I heard a clicking sound from up front

 

When's the last time you had a brake job?

 

How about you take off that wheel and start poking around?

 

I bought the car 2 months ago and was told the front brakes were changed and only the rears needed attention, should’ve checked the fronts too

 

If one of the caliper bolts fell out from insufficient torque when the brake service was done then the caliper can swing out of place and land on the wheel. That’s one possibility of many

 

Take the wheel off the problem should be obvious when you look in there.

 

squeaking sounds are normal when cold or the ambient temps are right. my 97 always had a squeak upon first application then went away as it heated up in the winter - but it should never actually lock up!

 

but that wouldn't explain why the car would roll fine when the engine is off unless the caliper unlocked by coincidence - good thought!

it's a head scratcher until the OP removes the wheel and inspects.

 

Yeah i agree folks. he needs to just pull the wheel and inspect. Likely some frozen pistons. Not a lot that can go wrong. However with the lack of understanding on the orginial question, it may make sense to have him take it to a shop, if he/she doesn't know what they are doing. Stopping is typically not optional! Not worth a risk of their lives or others.