Water damage is the main culprit for window replacement, and while it can be expensive to replace entire window units, the problem may only be a superficial one. Fortunately, there are several ways to fix this. If you can't afford to replace your windows, you can repair a single section instead. You can easily do this yourself, using a small screwdriver. Otherwise, you can visit a local home improvement store to find a window repair specialist.
For painted-shut windows, you may have to break the paint seal on the window frame. Cleaning the balance and tracks will cost pennies, but replacing parts can cost a few dollars. If you're having trouble with lead-based paint, you should contact a professional. Moreover, windows that were installed before 1978 may contain toxic lead paint, so you should be careful when handling them. You should also look for problems with the wood around the windows. If it's rotten, the gaps will allow air to enter your house.