lx188 ignition problem

You said "new solenoid."

Now I get it. For safety disconnect (+) from the battery. Disconnect "fat" positive wire that comes from somewhere underneath the dash to the starter solenoid and set it aside. Look closely under the solenoid...you'll find four terminals there. Two are small stake-on connections...leave it as it is. Now the other two are much larger copper looking and threaded. Look closely again...the one copper threaded rod/terminal that's the closest to the starter housing already has an eyelet connector and mesh wire on it. That is all that needs to be there. Make sure that you put a nut over it and secure it properly. Now back to the "fat" positive wire you've disconnected at the beginning. Guess where that wire go? You're correct...to the other copper looking rod/terminal under the solenoid. Secure it there with a nut. Now reconnect battery and test.

I did this but it didn't help, what am I missing

Starters 101.
The solenoid is just a switch, operated electrically using another switch ( key switch )

Now to save on wire the power for the mower ( and the key switch ) is taken off the power cable that comes from the battery
So the battery terminal on the solenoid should have 2 wires on the post.
One is the battery cable and thick
The other is the power feed to the mower & is thin
This second wire often gets overlooked or wired up to the starter ( switched ) side of the solenoid .

This thin wire goes up to the key switch but before it gets there it goes through a fuse.
The wire & fuse must be in good order for the key switch to work.

If you hooked the battery up backwards then the fuse blows
However if the battery is hooked up backwards the starter can still spin, backwards.
If it spins backwards, the bendex is in the wrong direction and the little gear wheel will not rise to mesh with the flywheel.

Several posts ago I asked you to check this and we are still waiting for an answer.
Remember that batteries come left hand & right hand + so double check for the + & - marks on the battery