The floor raises whenever you install a new hardwood or tile floor. Because the floor is higher, you have to raise the flange that connects the toilet to the residential plumbing.
There are a number of solutions plumbing contractors will perform for this plumbing repair.
You can install a new flange attached to the existing piping at a taller elevation. Closet flanges should be 1/4 inch above the floor height or the wax ring will not seal properly.
You can install an extension flange. This is a 1/4 inch flange that sits on the top of the existing flange and is siliconed to the flange. You can stack as many as four flanges to get the right height. Once you have the right level, use special plastic shims to level the toilet and make it sit tight to the floor.
Once you have leveled the toilet, you should seal the crack between the floor and the bowl of the toilet.
This is a minor plumbing repair for plumbing contractors should you need assistance.