D: recovery file

Hello,

Using an Inspiron 530 desktop computer, the D: drive is almost full and I don't understand how to reduce the size of the stuuf stored in D:. I found a solution, transfering the Dell file on an external drive. However, it is not a good solution. I also tried to increase the quota (from 10 to 25 Go) but my change was not followed by any effect. PLS, help me. Many thanks.