Part of house has very low power electricity out of no where
You (probably) have a bad connection.
This is dangerous - that connection will be heating up, and hot connections can start fires.
At a guess, you might be best served by just calling a pro, since it sounds like you are somewhat unfamilar with electrical work, but if you want to try checking it yourself, turn the affected circuit off at the breaker panel, and check every device on it, starting from the breaker panel and working away from it.
You'll be checking to see that all wire nuts and connection screws are tight, on both the hot and neutral wires.
If you have any devices which use &quot;backstabs&quot; (the screwless &quot;poke a wire in the back&quot; connections) just assume that any of those could be your problem, remove them from the backstab, and connect to the screw on the device corresponding to the backstab you remove the wire from. Screws are a much more reliable means of connection wires to devices.
Depending how long it's been going on, and how severe the problem is, you may find obvious signs of overheating (discolored wire insulation, melted or charred plastic) or you may not.
If your wires (the actual metal part) appear to be silver-gray rather than pinkish or brownish metal, you may have a bigger issue from a house of a particular era - aluminum rather than copper wiring.