How can I start my 1995 e320 if the ignition switch is bad

Who knows,can not guess for an answer

Maybe the motor is bad
Maybe the control circuit has issues

You really must know that all vehicle issues have
to be resolved with proper testing & you can't even
do that if you don't know how the system & components
work,so you need info before you start.

probably a bad ignition switch.

check to see if you are getting voltage to the starter solenoid from the ignition switch, it might be a bad starter.

VIN # ??
Engine # ??
Chassis # ??

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these cars before 1996 suffer with bad wiring.I would check and see if wiring was updated.

With the ignition on check there is Voltage on one side of the brake light switch with the brake pedal at rest , depress the pedal and there should be voltage at the other terminal . if not bad switch, if ok blown bulbs or bad connection.

It is a key issue most likely, try unlocking the car and taking a little more time to insert key into igniton than you normally do to see if that works. It can be a coding/timing issue in the anti-theft logic and most times replacing the key is all that is needed. otherwise it is the EIS acronym for electronic ignition switch which is a major control unit for the starting and anti-theft system.

Most likely will be the alarm system is cosign it. Armed alarm will protect car from starting to.

is it correct key? key and ignition barrel could be worn wiggle key around in ignition while turning? gently but fast wiggling.try lube in key slot also.
if not replace barrel and key

ihave a diesel e320 won't start