If adequate drainage wasn't installed when a basement wall was backfilled, this can lead to the accumulation of water on the outside of the wall. When this water freezes in the winter, it can exert tremendous force on the outside of the wall. This can lead to bowing, leaning and cracking. If the problem is allowed to progress, the wall could even eventually collapse. Other problems that also require attention can include scaling of concrete, deterioration of mortar in between concrete blocks, and excessive water leakage at the top or bottom of a concrete wall.
Bracing a wall with wood is a job that can be done by most homeowners. All you need is some very sturdy wood and a place to brace it against. The best way to do this is to lay a beam or sturdy plank flat against the affected part of the wall and then hold it in place with long planks or beams that are cut to the right length so they can be braced against the opposite wall. Wood of this sort is readily available. The job can be accomplished with a saw and a few people who are willing to help you.
Other methods of bracing are more expensive and more time consuming than using wood, but probably result in more effective and permanent repair. You can use steel to strengthen the wall by placing vertical steel beams against the affected area and bolting them to the wall, the floor joists and the basement floor. You can build a concrete form that encases the damaged wall and fill it with concrete, effectively fusing a new, undamaged wall to the damaged one. Most effective, and also most expensive, is an exterior excavation followed by removal of the entire problem area and replacement with new concrete or blocks and adequate drainage.
If you choose to brace a basement wall with wood, don't try to do it with cheap wood that you happen to have lying around. Some scrap 2-by-4s will have little effect on the force of a basement wall that wants to move. The bigger the wood you use, the stronger it will be. If you brace the wall using 10-by-10 beams, they will resist vastly more pressure than a couple of studs. If there is water coming through your basement wall, don't kid yourself that some caulking and patching will fix it. Serious problems require serious solutions.