Water is coming in, or was, and you want to know where from and who should fix it. Start with the page that matches what you see now: a drip, a stain, or a leak that only shows up in heavy rain.
Contain and dry: catch the drip, move belongings away, and dry wet areas and items within 24-48 hours. Look in the attic for stains and damp insulation.
Replacing a few damaged shingles is a standard repair, but unless you are experienced, hire a professional roofer for this work.
Look for cracked paint, discolored plasterboard and peeling wallpaper indoors, then check the attic and the ground, and avoid getting on the roof.
Sealant can close a small crack you can find. If the water shows up near a chimney or wall, or a sealed spot leaks again, plan on a roofer.
Metal roofs usually leak at the fasteners and at flashing and joints, not through the panels. A drip can also be condensation.
Look at the roof from the ground with binoculars, then in the attic for a drip trail or light coming through and wet or damp insulation.
Whether to go up and patch it yourself is your call. Unless you are experienced, hire a professional roofer for the roof-top work.
The water can be condensation, a failed glass unit or flashing that has let go. When and where it shows tells you which to suspect.
The water is probably getting in near the chimney, but the stain is rarely right under the leak.
A leak at a roof vent can come from the seal around the pipe, but the stain can sit well away from where the water gets in.
Scan the roof from the ground with binoculars, looking for cracked or curling shingles.
Look at ceilings and walls for cracked paint, discolored plasterboard or peeling wallpaper.
Yes, a hole can be fixed, but you should not be the one up there. Whether it takes a small patch or a larger job depends on how far the damage goes.
Stay off the tiles and the roof: walking on tile can crack it, and serious injury is a risk when you inspect a roof yourself.
Heavy or wind-driven rain can push water in at spots that stay dry otherwise. Leaks are rarely directly above the ceiling stain.
Look from the ground with binoculars and check the attic for a drip trail, and stay off the roof.
If it comes through the roof, a professional roofing contractor should do the closer assessment and the repairs. If a pipe froze or burst, call a plumber.
Water gets in at a weak spot: loose flashing, a pipe or vent, missing shingles, ice at the eaves, backed-up gutters, or an old roof.
Let the installer who did the work know the roof is leaking, and put it in writing. Your contract sets the real terms, so you need them on paper.