The egine starts and runs ,but u try to take the ebrake off it dies? or u try to move the control levers it dies? or engage the blade the engine dies and i dont know

Your seat safety switch is not working. If the seat switch isn't activated, ie. a person sitting on the seat, the safety system will stop the engine when the levers are engaged. There is probably only one lever safety switch, on the right lever, which is why the left one doesn't kill the engine. Check the seat switch continuity and the wiring for loose connections.

I find no such control as "engage the blades" for this model. There is "blade control" which is a blade brake release and engine run. The blade is in motion any time the engine is in motion, including during start. You hold the blade control lever to start and operate the mower, then release lever to stop engine and blade. Follow all safety precautions.
https://www.mtdproducts.com/equipment/OperatorManualDisclaimerView?storeId=10500&catalogId=20500&langId=-1&pdfLink=http%3a%2f%2fmanuals.mtdproducts.com%2fmanuals%2f769-04527.pdf&htmlLink=

ed, be sure there is nothing wrapped around the blades. lower the deck and be sure the belt is around all of the pullys. If the belt comes off one of the pulleys or the pulley on the engine it may feel normal but it wont engage the blades.

check for obstruction
be sure blades move freely
engine off spin blades by hand

Hi Digger:
I've two possibles come to mind for you to check.
1) Engine OFF - Make sure that all of the blades and pulleys can turn freely.
2) Engine OFF - Double check belt routing. Move engage lever ON/Off and look at what movement happens. It may be that the belt is on the wrong side af a mounting flange and binds when engaged.
Cheerfuls.

Chances are one of two sensors is broken or out of adjustment.
Either will cause engine shutdown when blades are engaged.
The first is the seat sensor. If you rise out of the seat with the blades engaged, the engine will die. That sensor is usually a switch located under the seat. The second is the Reverse lever (Or gear position). Newer tractors will shut off if operated in reverse with the blades engaged. This sensor may be more difficult to find, but it is usually another switch located around the gear shifter (or hydrostatic control lever).

get a new ignition switch and safety switch for your deck

check to see if a belt came off, it would go from bottom engine pully to deck lever pully then around blade pullys on deck. the pully under neth has to tighten belt to run blades the pully is ether solid to lever or has a cable that moves it make sure cable did not break hope this helps

sounds like throttle cable come off