I think the driver's side window glass has fallen off the guide.
If the window is no longer staying on its intended path the regulator may have been compromised. The regulator is the mechanism that raises and lowers the window and is powered by the window motor. If the piece holding the window to the regulator is broken the window may not follow its intended path and may be able to be pulled right out of the door. I would recommend having a technician from YourMechanic come inspect your window. If the regulator is broken I would have it replaced as soon as possible to prevent your window from shattering while driving. This is also a security concern if the window can be lifted from the door.
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