Texts I send are invisible to me (Nokia Lumina 521)

[WPCentral Question]

Previously, I couldn't receive texts or emails. The folks at T-mobile had me do a factory reset on the phone which made things better, for awhile. Now, I can type a text but when I press "send" the text disappears from my phone (as if I never sent it) even though the recipient gets the full text.

Um, huh? Please help! I'm about to throw this thing through the window of the phone store :-/