How to fix a hard wired smoke alarm that won't stop chirping

You don't say what kind of smoke alarm you have, or what kind of chirping, so i'm assuming it's a once per minute chirp which usually indicates low battery, but can also indicate that the unit has some other problem...if the unit is more than 10 years old you should replace the entire thing (per NFPA72, the national fire code, all smoke ALARMS must be replaced every 10 years)...if this is newer than 10 years, try replacing the 9 volt battery being careful to follow any instructions that may have come with the unit or may be printed on the back, top or sides...good luck.