I replace my battery in my 2002 lexus es 300 and not my car wont start the alternater is ok.

Replace the battery-cost 5 $

check the alternator output

It sounds like neutral safety switch (park/neutral issue) 1 question; Does the car have anti theft device? Same symptoms is anti thereof device is active.

check your fuse box. you might have a blown fuse

needs a starter. located under the intake manifold. big job for at home guy. takes average tech 4 hours or more depending how many if any he has done. Can be done in 2 hours by a good lexus tech.

your problem is the main fuse is blown under hood. it will be like a 100 or 120 amp fuse bolted in from sides of fuse/relay box.

You may have 'erased' some codes when you disconnected the old battery; Check with your dealer. Good luck.

try Walmart.  Also Auto Zone...most places replace them for free.

Most likely the crash sensor (located somewhere in the front of the vehicle) has triggered. Some can be re-set, most have to be replaced, otherwise the vehicle will not start.

Once the battery was placed backwards it may have sent a charge to the radio causing it to stop working, the alternater you should just try to either get it directly replaced same model..but if you want to try make sure all conectors are the same...other then that you can probly get a rebuilt one cheaper...rebuilt your current one will make sure its the same...and one major thing before you change anything make sure that the belt is on properly for the alternator and everything and just check if you are geting any charge from it