How do I restore my iphone from a previous icloud backup?

Restoring to an iCloud backup has to be done in the initial setup process. If you have any data on your phone now that is not in the backup that you want to save you'll need to do that first. Then go to Settings>General>Reset and tap Erase All Content and Settings. You will then go through the setup screens and when given the option, choose Restore from iCloud Backup (see image below). Be sure you are connected to wifi and your charger as this will take some time to finish.

You're welcome. Glad I could help.

How can I do a back up when wifi will not work on iphone 4s

You will do computer backup as it says in that article:

iOS: How to back up and restore your content - Support - Apple

You can't backup to icloud without wifi.

thanks for reply but itunes back up will not work error msg just says error occurred.

Use another computer that will not give you that message. Create another computer account that will not give you that message. No backup means you lose everything, but the stuff you synced. BAD .

I am having issues restoring from my most recent iCloud backup. I followed the steps you provided, but it keeps stating server is down and have to attempt to restore from backup iCloud later.