Roller shades are a great invention that take up little room and are very easy to use. Roller shades operate on a spring mechanism that is controlled by a ratchet mechanism, depending on how long you have had your roller shades they may need adjusting.
The Shade Won't Retract Fully
A roller shade that won’t react fully has a slack spring and can be fixed quite easily. Take the roller shade off when it has been pulled half way down the window. Roll the window roller shade by hand and then replace it. This time, when you pull the roller shade down, you should feel more resistance and it should retract into its proper fully furled position.
The Shade Snaps Back too Fiercely
This problem is the opposite of not retracting fully and the way to fix it is also the reverse. When the roller blind is fully retracted, take it down and unroll the equivalent of half the window length. Replace the roller blind and try to retract the length you have unrolled. You will find that it is not so fierce and you can repeat the exercise until the retraction is satisfactory.
If neither of these solutions work the problem might be with the roller mechanism which is more easily replaced than repaired.