The steps to troubleshoot and then if required restore a broken WordPress site depend on why you need to restore in the first place.
First we'll do some trouble-shooting...
Is Your Theme Compatible?
When WordPress updates there are no guarantees that all the independently developed themes and plugins that exist will work without issue. It is not WordPress' responsibility to ensure it works with everything out there. It is the developer's responsibility to ensure that their products -- themes and plugins -- free or paid -- work with WordPress and are updated as necessary.
Not checking theme compatibility is one of the common reasons why sites break and therefore need to be "restored". How do you know if it is your theme breaking your site? Go to Appearance > Themes > and activate the WordPress default theme. If everything functions properly -- you know it is your theme choking on the new WordPress.
Check Your Plugins next...
If you still have problems -- deactivate all your plugins and reactivate one-by-one to determine which is causing the conflict. Then, find a new plugin that is supported and updated by the developer.
My site is broken! How do I recover?
- My theme is not compatible with the latest WordPress version!
Don't look back -- look forward. Immediately contact your theme developer for assistance. If they are unresponsive, no time like the present to get your site on a premium theme where you won't have to worry about this again. Load up that new theme and customize it to your liking. Getting a theme compatible with the latest version of WordPress will "restore" your site.
- Did you change some theme files and break the site?
You should be able to go to your backup of the wp-content/themes/your-theme directory and FTP that to overwrite what is on the server thereby undoing your modifications and restoring your site. Don't have that backup? I bet you will moving forward! You can get help ($) or just upload a fresh copy of your theme and start over.
- Does your database need to be restored?
If you are using WP-DBManager plugin as I recommended here (If you are not; why not?), you can easily restore from your server to a previous backup of your database by going to Database > Manage Backups. Check the backup you want to restore and click the Restore button. The next step will be to refresh your permalinks. Go to: Settings > Permalnks and just click Save.
If you don't have a backup contact your hosting company. They may have a backup that they can restore -- don't be surprised if they whack you with a small fee for doing so.
- Was your site hacked?
Now this is a tricky one where you may need to bring in some help or contact your host to find out the damage caused and what is required. Regardless, having a full backup off your server will allow that process to be a lot less painful if a full restore is required due to files on the server being unrecoverable.
So, as you can see, using quality supported themes, keeping up with WordPress and having a backup process in place facilitates a hassle-free recovery!
At your service,
At your service,