I went to prison for 2 yrs and a half for pills can I still go to truck driving school

You need to take advice from a Lawyer.

Probably. Ask the school.

But, assuming you get a CDL, potential employers may ask about your criminal record.

Of course you can go to truck driving school, Felons can get a CDL. Just write the school a check and they will train you.

Finding a job will be harder, most of the better over the road companies will not hire with a record unless you have a lotof good experience. So expect to work for some local or regional companies at lower pay for a few years.