In all likelihood you have wooden sash windows which are hung on cords and weights. Your weights may not be attached to the sashes any more. I have made repairs to the sash cords and had success. I found a guide on "Repairing Sash Cords" at https://www.thisoldhouse.com/how-to/how-to-repair-sash-windows. There are also good videos on UTUBE showing how to repair sash cords. Properly balanced on cords and weights should keep your windows open.
Our 14 year old cord controlled blinds are all giving us trouble with raising and lowering and tilting. Many of the top mechanisms are coming unglued from the top. I ...
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How old are your Windows? Different age windows have different counter balance mechanisms.