OK there are different drives that are used in the computer and you kind of did not explain exactly what drive you are referring too. Although I assume that it is the CD/DVD optics DISC drive and not the Floppy DISK drive or the hard drive DISK as the latter two do not close.

If you are refering to the optical drive (CD/DVD) drawer then all you need to do is slightly push the drawer closed and it will automatically retract within itself. The same button used to open the drawer is the same one used to close the drawer as well.

If you have burning/viewing software installed then with in the toolbar (either view or edit) will be an options setting and it should allow the opening or closing of the optics drive as well