How do I raise the blades

check belt and pulleys --if belt to loose wont turn blades to cut the grass

Sharpen the blades,very sharp,and lift the deck one notch from where you normally cut.Some times the blades will get dinged,or the ends of the blades will dull.

I have seen dull blades, blades not installed right and an un-level deck cause that.

Hope this helps.

When using a bagger, you need correct blades on mower or Worn blades will cause the deck not to get the vacuum needed for the bagger to pickup.

Set the mower on a known flat piece of concrete. Now look at the deck and the support connections where the deck hangs from from the mower. Should be adjustments such as pins with clips or threaded bolt hangers which will allow you to raise or lower the corner of the deck which is low or high. Conversely you could have put a blade in upside down or left out a washer making one blade higher than the other. Usually an owner's manual will detail this process. As you just changed your blades, as opposed to wear and tear, likely you did not put it back together exactly as you took it apart.

Sounds like you may have made a common mistake, getting one or both of the blades upside down.

leveling bolts hang from each side deck by frame...tightened up and level...will give you some more room....be sure the blades are not bent.

Either the deck is uneven or one of the blades are upside down

It sounds to me that you need a new mower deck drive belt, or your blades need sharpening. If the blade edges are rounded, they won't cut butter... Also, when mower is off, check mower deck drive pulleys to make sure you don't have any that are locked up or are dragging. You can check this by pulling the belt away from pulley and spinning the pulley by hand. MOWER MUST BE OFF before attempting any of these checks. You would be surprised how many people would try this with the mower running.
Hope this helps