Find the window latch or lock and release it
Lift, slide, or crank the window open depending on the type
If it is stuck, check for paint, dirt, or debris blocking it
Gently wiggle the frame while applying steady pressure
Use a silicone lubricant on moving parts if needed
If the window is painted shut, carefully score the paint seal
Check for any safety locks or child locks and disengage them
If it still will not open, inspect for damage or call a professional