A phone that will not charge is usually not a broken phone. Most charging problems come from the cable, the adapter, or lint packed into the charging port, and those are cheap fixes. Work through the steps in order, cheapest first.
The fixes, in order
Try a different cable. Cables fail more than anything else in the charging chain. They bend at the ends thousands of times and break inside even when they look fine. Try a cable you know works with another phone. For iPhone Lightning cables, look for MFi certification. For USB-C, use a reputable brand.
Try a different adapter and outlet. Plug straight into a wall outlet, not a computer USB port, a TV, or a car port, which often supply much less power. Try a different outlet too. A 20W or higher USB Power Delivery adapter is a good test for most modern phones.
Clean the charging port. Pocket lint packs into the port until the plug cannot seat fully, and this is one of the most common reasons a phone suddenly stops charging. Turn the phone off, shine a flashlight into the port, and gently lift the lint out with a wooden or plastic toothpick. Never use metal pins or paper clips: they can scratch the contacts or short the port. The cable should click in firmly afterwards.
Take the case off and try again. A thick or misaligned case can stop a cable seating fully, and it can also block wireless charging.
Restart the phone. A frozen charging service or a crashed app can stop the phone noticing it is plugged in. Restart, then plug in again.
Try wireless charging. If the phone supports wireless charging, put it on a pad. If wireless charging works but wired charging does not, the problem is the cable, the port, or the wired charging circuit.
Check for a moisture warning. If the port is wet, phones block wired charging until it dries. iPhone may show a “Liquid detected” alert, and Samsung Galaxy phones show a moisture-detected warning. Unplug, tap the phone gently against your hand with the port facing down, and leave it in a dry place with airflow for at least 30 minutes before trying again.
Check the 80% limit. If the phone stops at 80%, that is usually a battery-protection feature, not a fault: Optimized Battery Charging on iPhone, Adaptive Charging on Pixel, or Battery protection on Samsung. Turn the feature off for the day if you need a full charge.
Update the phone. Software bugs can break charging, and makers fix them in updates. Check Settings for a pending update.
Stop using the phone if the battery is swollen or the phone is dangerously hot. A bulging back, a lifting screen, a chemical smell, hissing, or smoke are danger signs. Stop charging it, do not puncture or press on it, keep it away from anything flammable, and get professional help. Never open a phone battery yourself.
If nothing works
If you have tried a known-good cable and adapter, cleaned the port, restarted, and updated, the problem is probably hardware: a damaged charging port, a failing battery, or a fault on the charging circuit. A loose port that only works when the cable is held at an angle usually needs a professional port repair. If the phone is still under warranty, contact the maker before paying for a repair.
Common questions
Why does my phone only charge at a certain angle? That usually means lint in the port or a worn cable. Clean the port gently with the phone off, using a wooden or plastic toothpick, and try a different cable. If the port itself feels loose, the port is probably damaged and needs professional repair.
Why does my phone stop charging at 80%? That is a battery-protection feature working as designed: Optimized Battery Charging on iPhone, Adaptive Charging on Pixel, or Battery protection on Samsung. It pauses at 80% to slow battery aging. Turn the feature off temporarily if you need a full charge.
My phone says liquid detected but it never got wet. What should I do? Moisture can get into the port from humidity, sweat, or a steamy room. Unplug the phone, tap it gently with the port facing down, and leave it in a dry, ventilated place for at least 30 minutes. Do not use a hair dryer, and do not force charging while the warning is showing.