If I restore my iPhone will I lose my apps, photos and other data?

When I try to open the apps that I downloaded on my iPhone they immediately crash and return me to the home screen. I've tried switching my phone off and on and that hasn't helped and I've checked to see if all my apps are in date in the app store and it says that all my apps are in date in my app store. And these apps that I've got on my phone have always worked since i've downloaded them a year ago.

Added (1). If restoring my iphone will not resolve the problem can anybody suggest anything else that I can do?

If you sync it regularly (and right before a restore!) in iTunes, you will not lose anything.iTunes creates a backup of everything. When you restore it, be sure to restore it to the latest backup in iTunes, and not as a new phone. I have done this a couple of times.

Check this: http://support.apple.com/.../kb/HT1414