All of a sudden all my rides are breaking down and no mechanics are available.  What is happening?  I looked up cheats and it said to rename one of the peeps "Frontier"  I did it and nothing happened. 

Make sure your mechanics are not lost and there are paths leading to every attraction. Also make sure you've hired enough staff.

Like brad said just make sure your mechanics aren't lost and that you have enough

From the description, it sounds like the Frontier cheat keeps rides from breaking down, but it doesn't actually fix them if they're already broken. They shouldn't break down again as long as Frontier is in your park, but you'll need help from your mechanics first.

If you have some mechanics in your park and they aren't fixing your rides, make sure that all of your ride exits are connected to the path, as this is how mechanics enter the ride to fix it or inspect it.

Setting patrol areas for staff, though not a requirement, will keep things running more efficiently since your mechanics won't be able to wander too far from the rides you assign them. RCT3's patrol system is actually the best in the series because it allows you to select each individual path square that your staff member can walk on.

I'd take what Terry, and Brad and others said; make sure all of your exits and paths are connected. Set up parole areas for rides - say, one mechanic for each ride. That one mechanic goes to only one ride. Another ride also has a mechanic that goes solely to that one ride. Make sense?

Good luck with fixing your park, mate.

Dang Blaze, I didn't know his rides were hardened criminals. At least you're trying to help him set them up with *parole* though

From the description, it sounds like the Frontier cheat keeps rides from breaking down, but it doesn't actually fix them if they're already broken. They shouldn't break down again as long as Frontier is in your park, but you'll need help from your mechanics first.

If you have some mechanics in your park and they aren't fixing your rides, make sure that all of your ride exits are connected to the path, as this is how mechanics enter the ride to fix it or inspect it.

Setting patrol areas for staff, though not a requirement, will keep things running more efficiently since your mechanics won't be able to wander too far from the rides you assign them. RCT3's patrol system is actually the best in the series because it allows you to select each individual path square that your staff member can walk on.

Ok I've given every mechanic an area to patrol even have two or three mechanics in one area that is congested.  All rides have entrance and exits. Frontier is still in the park but rides are still not getting fixed.

You may have to demolish the prebuilt in-game rides and replace them. Not sure what else you could try, maybe fire all the staff and start with fresh staff. Have you tried manually sending a mechanic to the rides in question? When you open the window for each ride there will be an option to call a mechanic.

thanks to all your help I was able to find the culprit.  One ride did not have a good enough entrance and the mechanics couldn't get to where they were needed.  Everything is working a lot better now.  I would like to upload this Park and I welcome comments.  I can accept constructive critisim  but don't tolerate sarcasm very well.  This is my first Park and would like to move on to others including Coasters etc.   Thanks again for all your help.  The Park is named John's Wonderland in case you need to know.