[REALLY NEED HELP] Flashtool doesn't allow my Xperia U to flash ROMs/kernels topic

Hi...

I wanted to flash a kernel, so I entered into fastboot mode with the "up" volume holded, and then, the blue LED appeared, but then, it just dissappeared! So Flashtool didn't flash anything.

Again, and again, one time and other, and again.
I get bored and decided to flash the ROM I had in CWM, so I flashed it from CWM and now, I cannot turn on my phone cause it makes bootlogo.
Flashtool still does the same thing with my device when I'm trying to flash any Stock Rom or Kernel.

Please, I need the phone for daily usage and for tomorrow.

What can I do? I can enter to CWM but I don't know more things to do to solve this problem...

Help, please.

:rolleyes:

Need your opinions on flashing different roms/kernels often topic

Hello,what's your opinion on flashing different custom roms and kernels often? I mean every about 3 days or every week (sometimes even needed to flash on day two times because some roms or kernels are unstable and need reflashing) So what do you think about it? Does flashing somehow affecting phone? Or if you're flashing everything correctly (I mean for your specific phone model and etc..) won't have any affect for you phone?
Sorry for stupid question,but I discovered so much amazing roms on Nexus and I just want to try quite a lot of them,so that's why I'm curious to see your opinions about flashing roms.:cyclops:

SPH-L720T ROMs/Kernels topic

Anyone know what kernels/ROMs work on the 720T version of this device?

Thanks