How do I reseal a drafty window without replacing it?

Clean the window frame thoroughly, then apply weatherstripping foam tape or V-strip (tension seal) along the sides and top of the sash where it meets the frame. For gaps between the frame and wall, use rope caulk, which is removable and good for seasonal use, or silicone caulk for a permanent fix. If the window rattles, the sash is too loose, so adding foam tape to the stops will tighten the fit. For older windows with cracked glazing putty around the glass panes, scrape out the old putty and apply fresh glazier's compound. Draft snakes placed at the bottom sill can also help temporarily while you work on a more permanent solution.