Since you mentioned that all of your other apps are working, but your Gmail will not load, I would recommend removing and then readding the Gmail account to your device. This can "reset" the Gmail with your device, and resolve your issues. Please follow these steps.
Accounts & Sync
Touch the Gmail account
Select Remove or Cancel
To re-add, please follow these steps:
Please post back with any results. Thanks and have a good day!
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