Could you give us your computer's specifications? That might help in finding your issue.
From the looks of it, you have an HDD that's had quite some working time. HDDs simply wear out, that's something you can't stop and sadly can't fix. Defragmenting the HDD sometimes helps a bit, but at one point that doesn't fix anything at all. Something defragmenting a harddisk will even contribute to the wearing process of the HDD.
If I were you I'd get an SSD and install your operating system and stuff you want to use a lot on that. The HDD that you are using right now could still serve as a secondary disk, to store stuff and transfer stuff to your new HDD/SSD. Why an SSD? Because SSDs simply -are- a lot faster, and will replace the HDD in the future. Also, for some reason the HDD price has gone up a lot, while the SSD price is still the same, or cheaper than it was 5 months ago.