What can i do to strengthen and beautify our backyard retaining wall?

It looks like some of the mortar between the blocks has deteriorated. It may have to have some of the blocks replaced. Check with a mason/contractor for suggestions.

Who's wall is it? Looks like structural damage. If it belongs to you call a mason. it may need to be removed, soil behind it excavated, and wall rebuilt. Bracing the wall would just be a band aid repair.

I agree with William. It probably wasn't installed correctly in the first place. You need to have the wall tied in deeply with the slope behind it. The wall will continue to move unless it is taken down and redone. Lots of $$. A Band-Aid repair will be dangerous as the slope will continue to move (nature at work) without a proper fix and it could blow out causing major damage to both properties. The damage at the bottom is of concern.

determine whose wall it is first. Or if on the line, will your neighbor split the repair cost. If it’s yours and on the line, you will need permission to dig up your neighbors side, or move the wall, or part of it on your side. look at the option or repairing just a section of it with maybe a curved out part?

Absolutely a very serious problem. A heavy rain will put more pressure on the wall and it will fall and damage even more of the wall than is affected now. You need to get a structural mason to undertake this problem quickly. Once the damaged section is repaired they can cover the entire wall with concrete and you can stain (or color) it to look more natural. Your local tax assessors office might be able to determine who built the wall. If it is that high there should have been permits.

A solution that might work. My son's basement wall did this, and he put poles to hold it. Therefore, buy the right kind of poles and paint them the color you like. Dig holes and put pole in, add sacrete and water to concrete them in. Need a lot to keep wall from pushing them over. Then paint the blocks different colors or just one. The poles will be part of decoration if you space them right. You might even be able to add small flower baskets or bird feeders from poles. Maybe a crazy idea.

Having just been through this...(and much more), the most important is that your wall is currently experiencing a structural breakdown. I wonder is deadmen were used or used improperly. Secondly, I see no place for drainage at all. There has to be a way for water to escape from behind that wall. Thirdly, If you get a heavy rain or experience runoff from your neighbors property, I would not want to be close enough that the wall could collapse on anyone, a fur baby or patio set.

Looking at your pics, I’d say there is no fix for this. I highly recommend getting a certified retaining wall company to put a new, proper one in.

https://www.youtube.com/watch?v=oSlUy18Vttk&feature=share

https://youtu.be/aUfaOQyH6nk

I concur with everyone else here. You need a mason, quick. Depending on the height and length of the wall, and how much soil it is retaining, you may need an engineer. I researched this a bit myself, and there are companies that make retaining wall systems that might be a source of information for you. If your neighbor is above you and it's holding up his property, it might be his wall to fix, but it's a danger to anyone in your yard if it comes crashing down.

As Hope said, you need some drainage for the wall. Any mason you hire must use the proper drainage tubes, wrapped in landscape material and buried in gravel, to divert water out from behind the wall, to alleviate the hydrostatic pressure.

Been there. The wall needs to be rebuilt from scratch. It needs to be back filled with gravel. Also a French drain on the upside would benefit. Coat with foundation sealant on the upside, as well. Concur with William