To run a memtest, download it here ---> (click here
Unzip it to where you can find it. This is an image file and needs to be burn to a disc and be bootable. For this get a program called ImgBurn.
Use "Write File Image to Disk" and find the image you unzipped. Once it's done burning leave the CD in your computer. Boot from the disk to run the test. If you don't know how, ask.
For a check disk scan go to command prompt and type "chkdsk /r" without the quotes. Restart your computer and it will scan before you log in.
To get to command prompt go to Start>Programs>Accessories>Command Prompt (be sure to be logged in as administrator).