Any time repairs are done to your walls--such as filling in a scratch or crack, repairing a pipe leak or fixing an electrical problem--repainting the affected area is part of the process. If you like the wall colour and don't want to repaint the entire room, you need to find a paint colour that matches what you already have. If you don't have the original paint can in the garage, there are still ways to match the colour and avoid a major painting job.
Wash your walls thoroughly with a mild cleanser. You need your walls to be clean to get the best match.
Use a utility knife to scrape away a small sample of paint near the area you plan to repaint.
Bring your sample to a paint store to match the colour. Many paint and home improvement stores offer computer colour matching services. Ask the paint store you visit if this service is available. If not, ask them to mix up a slightly darker, richer colour for you based on the paint chips.
Buy pure white paint while you're in the paint store to help you match the colour on your walls.
Try out the new paint colour on your walls with a paint roller. Don't use a paintbrush. Let it dry for 30 minutes to determine if it is too dark. It most likely will be.
Mix together 1 tbsp of the coloured paint and 1 tsp of the white paint you bought. Paint this mixture on the wall, and let it dry for 30 minutes.
Continue adding more or less white paint to the mixture until you come up with the same colour that's already on your walls. Make sure you pay attention to the ratio you're using, so you can mix together enough paint for the whole area.
If you get a colour match that works, make sure the paint store prints the tint formula on a lid label for easy reference.