I lost my keys then got them replaced but car wont start the car turns on the engine wont turn over

Check the security (anti theft system). If the coding does not match the key the car wont start. This assumes that the engine can turn over with the starter.

stock engine?
i did not decode that, at all.
has power? (what 12vdc power or engine power)
turn key it wont start but does it crank.??????? fast..
and lose power, what power is lost 12vdc power or engine runs but lost power?
the power is back what power? name something, specific,
like 12vdc power, starter power, engine power.
the starter wont work, i take that its silent?
or
starter spins but engine dont?
or starter clicks
or starter, is weak
or ???? try to be clear,

no engine stated.
no transmission.

if stick shift the clutch switch must work or the starter will be dead.
does that help
ever hot wire a starter, see this.
http://www.fixkick.com/nocrank.html

if engine will not crank, say that.
then say sounds. it makes if any.

There could be some play in the ign switch allowing the voltage to be lost in certain position. Turn key to run position, do start engine. Turn on blower fan, turn signal, radio . Wiggle the key to see if they go off with key movement. If so replace electrical switch behind the key and tumbler

Have you lost the chip out of the key?? try the spare key before you go any further

Wont turn over after replacing battery ??????? When you turn the key to the start position nothing happens ? Have to ask because won't turn over means something else to somebody else .
You have a engine cranks - no start or you have a no crank - no start .
Do the light's on the instrument cluster come on when you turn on the key ? Do the Headlamps work ?

Battery Disconnect or Replacement Problems

sounds like the timing belt broke or jumped time

Was it the fuel pump? If not I would consider the charging system ie) battery, alternator or both.

look at the anti shudder valve (asv) look at pics on net. Its an air intake valve that shuts in order to stop the engine. It sometimes sticks shut. Syptoms are engines tries to fire but then turns over very freely but wont start. If it is this the whole air intake system needs de coking.

No spark, ck the crank position sensor. bolted on engine at the front crank pully. Good luck. unplug and plug it back in to clean the wire connection/

check the key that year modle has a chip in the key and if it was around something magnetic it could have lost it's programing. If that is not it the there is a fuel rail with what looks like a air pressure valve. turn the key on and press that valve if fuel sprays out it is your key. If fuel doesn't spray the it is your pump