Intro
If a vinyl piece has come apart from its neighbor, the solution is often to push it back up until it locks in place (see Replacing a Panel Section: Step 5).
If many of the pieces are coming apart or buckling, they may have been installed with nails driven tightly; nails should be loose so the material can expand and contract. If that is the case, you may need to remove the siding from an area and reinstall it.
If you need to replace a vinyl panel or part of a panel, check your garage or basement to see whether the installer left extra pieces for repairs. Otherwise take a sample to a siding supplier and look for a close match.
Even if you find an exact replacement, the siding on your walls may have faded, meaning that the new pieces will be noticeably darker. If the repair is on a highly visible portion of the house, you may want to remove a piece from a less-visible part of the house (perhaps in the back or behind a bush) and use that as the patch; then install the recently bought piece at the less-visible location.
Prestart Checklist
Time
Less than an hour for most repairs
Tools
Hammer, tape measure, zipper tool, flat pry bar, tin snips, utility knife, caulking gun
Skills
Simple cutting and measuring skills
Prep
Check the siding closely for further damage to determine how large a section of siding needs to be replaced.
Materials
Replacement siding panels, butyl caulk (or gutter caulk), duct tape, materials for bracing a patch temporarily