What std will ampicillin cure and is chlamydia one of them?

Chlamydia can be easily treated and cured with antibiotics. A single dose of azithromycin or a week of doxycycline (twice daily) are the most commonly used treatments.
If untreated, chlamydial infections can progress to serious reproductive and other health problems with both short-term and long-term consequences.
You should see your doctor is you suspect you have chlamydia.
For more information see: https://www.drugs.com/cg/chlamydia.html

Ampicillin is not typically used to treat Chlamydia.
Ampicillin could be used to treat uncomplicated gonorrhea - however its use is limited because of bacterial resistance. To reduce bacterial resistance ampicillin should only be used in circumstances where it is known to be effective.
https://www.drugs.com/pro/ampicillin.html