A rotted wall is rarely just a rotted wall. Usually there is a moisture problem that must be addressed first. Double check for tunnels that indicate termite damage. Termites can destroy a home quickly. They love the damp and rotting wood that moisture provides. In the case of a wood floor, usually the floor rots away with the wall. If your house is built on a slab, check the condition of the concrete at the edge, is there anything that could cause water to stand under the wall plate? Ridges, pits, holes.. does the concrete stay wet there? Plumbing lines also are likely causes of rot in walls. A slow leak can cause a huge amount of damage. Roof problems, clogged gutters, siding that is not installed properly, can also cause unbelievable problems.
Once you determine the cause, then you need to determine wether the wall is load bearing and wether there are any critical load points above the damaged area. Load bearing walls usually run parallel to the gutters on your home, but can be anywhere and run in any direction. Critcal load points are typically supports for beams, corners, supports for door headers, below upstairs rim joists, under valleys where the roof loads may be concentrated.
This is one of those times when a contractor needs to at least look and see if there is anything to be concerned about. No one on this forum can tell you with certainty wether you can do this repair or not, removing and replacing a section of wall can be very dangerous when you have no experience. At the very least, post a few pictures of the wall inside and out, get anything that may be above the wall in the shot from outside and get the ceiling and the floor in the inside shots also. Ripping out walls can land you with a mess of cracked drywall and sagging joists that will require a pro to come in and fix. Jacking up walls and resetting beams is not typical DIY project rated.
Welcome to the forum,
with a little more detailed information and a few pics,
we may be able to help..