First, make sure it isn’t just a camera setting issue. On many cameras, the built-in flash only pops up automatically in certain modes, or when flash is enabled and the camera decides more light is needed. Try a full auto mode or use the flash pop-up button if your camera has one.

If it still won’t open after being physically blocked, the pop-up mechanism was likely damaged or the spring was displaced. In that case, the proper fix is service or repair at a camera shop or authorized service center.

You may be able to press the flash-release button and gently lift it manually as a temporary workaround, but don’t force it. If it won’t stay in place or doesn’t operate normally, stop using it and have it repaired to avoid further damage.