Hlo....I'm a girl and I have 18 yrs. I'm suffering from constipation since 7 days. I'm drinking lots of water but it's not working...Plz help me?

Many possibilities. You may need to be aggressive to begin improving. An enema, held for 15 minutes to allow better results & released can begin creating space at the end of the intestines for things to start moving. Add to this a bulk wetting agent like polyethylene glycol solution (miralax) uses daily for weeks & you may get on track. The enema may repeated daily if things don't start moving.Otherwise see your doc.
Constipation. Try high fiber diet. If it does not work may try otc miralax (polyethylene glycol). Seek medical advice if problem continues.