How can i tighten a tooth that is loose from bone loss?

Splinting: Periodontal splint. Using wire in the lingual surface and bonded to the teeth with resin. Or using glass fibers instead of the wire.

Bone loss and an: Associated loose tooth is not something for u to correct (tighten), your dentist needs to be in charge. After a thorough exam, bite adjustment, splinting of the tooth(teeth), periodontal disease treatment/surgery, medication, and other things may be recommended. There are likely other teeth involved as well, they just aren't noticeably loose yet. Please seek professional care as soon as you can.

See specialists: Your best course of action is to see a prosthodontist for evaluation of the bite forces and a periodontist to evaluate the tissue / bone remaining. Between these 2 specialists, you will receive expert assessment and guidance. Often, there is insufficient bone remaining for a good long-term prognosis, and an implant is the best option -- provided there is sufficient bone. Best of luck.