There are several types of vertical blinds covering doors and windows: fabric, vinyl, panel. By far the most common and cheapest kind of blinds are vinyl, that come in different colors and shades.
Vinyl blinds have one significant flaw: the top ear of the individual blind (also conveniently called: "slat") easily breaks off at the most unexpected time from the slightest movement.
An easy method to prevent this or to fix it is to get transparent repair tabs and attach them before hanging the slat. They can be used either to repair broken slat, or better attach them to the new one to strengthen it and prevent it from breaking.
When search for these you have couple options: either plastic "repair tabs" or metal "vane savers" or "repair clips". Depending on your situation you can chose which ones to use.