Hi I have a 1998 es300 and my mother thought she lost my key called a locksmith and he "flashed" the ecm but his keys didn't work so I found my original master key and the locksmith said if should start the car but every time I try to turn the key to the own position it cranks but doesn't start any advice to fix this issue?

 

If the locksmith programmed the ECU properly (doesn't sound like it) then the original key can be programmed to start the car. Check Speedkar99's Youtube channel he has several vids on the subject.
https://www.youtube.com/user/speedkar99/videos