why does my 2000 lexus es300 turn over put does not start?

Hello, There are many, many causes for what is termed a 'crank-no-start' condition. The first thing you should do any time you have this issue is listen. Do you hear the fuel pump running when you turn the key to run without trying to start the engine? If you do not, check the fuse for the fuel pump, then check for power at the fuel pump. If you are getting power and ground at the fuel pump, but the fuel pump does not run, the pump is likely the issue. Test first, then replace.