Loud screech noise from deck area

Your lawn tractor will have a lever that raises and lowers the mower deck which houses the two cutting blades. By lowering your mower deck to the desired cutting height, the blades should automatically engage. By raising the deck back to it's highest position, the blades will automatically disengage. Should be simple enough. You can consult your mower manual. If you don't have one, you can easily find it online using the make, model and year of the lawn tractor.

Is your spring hooked up.

Check your BLADE BRAKE FOR PROPER ADJUSTMENT!

After hitting a tree root, blades will not cut when I press to engage

Something is locked up underneath, something is preventing your belt from spinning. I recommend going under and inspecting the blade area and also belt area especially if the deck is full of debris. You might even have a frozen bearing or something like that anyhow you need to do a little investigation, pronto buddy. Good Luck

possible something binding on the deck one of the mandrels may have a burnt bearing

With blades on and engine off reach under and wiggle each blade up and down. If you have excess play you will need bearings.

Frozen idler pulley under the tractor frame or frozen or damaged bearings on the deck spindles. With no belt tension on these items they should spin freely. If you have the know-how you can fix the problem yourself (parts are available at sears.com or elsewhere), otherwise you will have to bring it in for repair.

No,You need to park on a level area and lower the deck to it's lowest setting and adjust the deck with the large butterfly nuts on each side,just under the foot pan,just loosen and let the adjusters fall into place,Tighten back up and it should be set.You may need to do this more than once.

Is the belt on the pulleys ? If so your cable is broke its what engages deck belt