Over time, hardwood floors can suffer damage from foot traffic, exposure to moisture and moved furniture. Other things that can damage hardwood floors include spills and pet accidents. Hardwood floor repair can be a relatively simple process depending on the extent of the damage. If you have solid hardwood flooring, things like dings and scratches can be fixed by refinishing the floor. Note that engineered hardwood floors tend to have a thinner top layer and cannot be refinished as often.
However, you shouldn't count on refinishing as your primary fix for hardwood floor repair. Refinishing can be a long and difficult process for an inexperienced handyman. You should only resort to refinishing your hardwood floors when the scratches are deep. Small surface scratches can often times be fixed simply by applying a varnish (or polyurethane) that matches the floor. Apply the varnish directly to the scratch using a q-tip or small brush. Once the scratch is adequately stained, you'll need to apply a coat of wax and then buff. You can use an electric buffer or buff the scratch by hand.
If you have a lot of noticeable hardwood floor scratches and can't tend to each one individually, having your hardwood floors refinished may be your only option. Keep in mind that refinishing hardwood is no small feat, and can result in a large amount of dust within your home. You'll need to keep your kids and pets out of the area until the hardwood refinishing process is complete.