Apps Greyed out for iphone in itunes

In iTunes, try clicking on iTunes Store on the left sidebar, then click on your Apple ID on the top right, sign out and then sign back in. Now connect your phone and see if your apps will sync.

Did you also try signing out and back in on your phone (Settings>Store>Apple ID, tap the ID, sign out, sign back in)?

Have you gone to your purchase history in the iTunes Store on your computer? Should be on the right-hand side of the iTunes Store under Quicklinks. From there, you can download all the apps that where purchased your Apple ID right into your iTunes library on your computer.

I don't think the problem is getting the apps into iTunes; they're already in the OP's library. The problem is they are greyed out and he can't sync them to his phone.

If they are greyed out then that means they aren't being found and the source is missing. It's not like you have any good ideas. Also, I highly suspect that the OP isn't telling us everything or hasn't actually gone through all the steps.

OP, when you uninstalled iTunes did you remove all of the components as well? There are 6 total. Also, is your computer authorized? Do you get any kind of error messages when trying to sync? After you select "sync apps" do you actually hit "apply" and then sync?

I wasn't critizing you, I just was only trying to clarify the problem in case one of us didn't understand it. BTW, greyed out doesn't necessarily mean the source is missing. This can be caused by many things (restrictions on in phone, Apple ID not authorized, etc.).

Grey means he can't edit it or make changes to it usually because the source can't be found or the feature/option isn't allowed. The OP is leaving out something important. You can't just transfer purchases from iphone to computer and then not be able to sync them back. The OP may even have parental restrictions set for Apps within iTunes. This can be checked from Edit>Preferences>Parental.

OP, what happens if you right-click on one of the apps and select "get info?" What's the account name and the Apple ID that was used to purchase the apps? Is iTunes up to date? Are the apps even compatible with iphones?

I get the same greyed out apps when I try to sync through my MacBook Pro. However on my MacPro Tower this is not the case as all the apps show up.

Here is the solution, Go to your iphone>Settings>General>Look for "RESITRICTIONS". You might have to scroll down. Once you find it, click it then (scroll down) look for "Installing Apps". If that is OFF, turn it ON. Press the home button. Connect your Iphone with Itunes then go to apps. And After 5 seconds it will be able to let you tick or untick the apps you want to sync!

How many apple IDs do you have on your iphone? If the are two or more IDs, you have to log in and download all apps directly from itunes. I guess if you have apps from more than one account, you gonna end in this problem. I tryed this one and worked for me. Luck

Did you uncheck SYNC APPS in iTunes APPLY at the bottom right and then try rechecking SYNC APPS and APPLY again?

One thing you have to remember if that box with your apps is greyed out and you have apps on your device then you will need to transfer purchases first (http://support.apple.com/kb/HT1848)