What operating system are you using?
What processor do you have and with how much RAM?
How much free, clean, freshly defragmented space is on your hard drive?
I've been tearing my hair out all day over this issue, trying to rack my brain to remember what else could have been changed on my system in the last week that made Premiere suddenly decide it didn't want to launch.
I finally remembered that there was an Nvidia driver update! I rolled back the driver to the previous one and viola, Premiere Elements 12 is back in business! If you have an Nvidia card and updated the driver since the last time you used it I would do the same. Open up the device manager, select your Nvidia card under the display adapters option and in the drivers tab select, "roll back driver" and it should roll it back to the previous version unless you manually uninstalled it.
That's great news, mistax! Glad you're up and running again.
I don't want to roll back to be honest, I'm a gamer and need updated driver AND Element to edit my clips.
Perhaps if we make some noise on the Nvidia Forum it will get some attention. I've created a post there, feel free to jump in.