My hard drive is very slow and when I play League and CS:GO it loads very slowly?
How can I fix it without buying a new one? I don't have the money to buy a hard drive
You can try defrag. Depending on what hdd it is there may be a utility for it however these may cause a slowdown too. There is not much else you can do. Besides deleting some files. (May make a very small improvement on non ssd)
What is the model of the drive?
As the HDD may have some issues, it may be a good idea to test it with a brand specific tool. If the results show that there is something wrong, back up the most important data that is stored on the drive.
Apart from that, you can try running Windows Disk Check: http://www.sevenforums.com/tutorials/433-disk-check.html