I have no vent in my restroom.Now I have mold stains on ceiling...HELP

You need to get rid of the mold with bleach or a mold killing product. Then invest in a good bathroom fan vented to the outside. If you don’t install the fan, you will continue to get mold. Fans are relatively inexpensive. The installation costs will be higher.

I don't have a vent, either. I did install a ceiling fan and keep the door ajar when showering, it helps. I occasionally use a sponge mop and diluted bleach solution to clean the ceiling, they are pretty high. Just wipe them down and try to avoid the steam buildup.

Try spraying Bleach directly on the mold. I know that works in other places.

Use bleach...call an electrician to install a fan that vents to outside, shouldn't be that expensive $100.00

Clean up the area with bleach water to help with the stains and follow with vinegar sprayed generously anywhere you had the mold or mildew. The vinegar will kill the spores so that it will take longer to get it back while you try to increase the circulation in the bathroom. Running a good fun in the bathroom will also help until you can get the right fan for the room put in.

Bleach does nothing but whiten the mold and spreads it around. Vinegar will kill mold spores, bleach does not. Never has and never will.

http://restorationmasterfinder.com/restoration/what-kills-mold-bleach-vs-vinegar/

https://www.servicemasterrestore.com/blog/mold-damage/mold-myths-will-vinegar-kill-mold/

Until you can shop for an exhaust fan and have it installed properly, crack a window if available, leave the door ajar, bring in a portable fan to help with ventilation.

Leisa is right put an exhaust fan in now. You will continue to have this problem until you get a fan to pull the excess moisture out of there. First spray the existing mold with vinegar to kill the spores. Then wipe it down with bleach. But bleach alone won't kill mold spores.