reintall in spanish

i had installed wp fine in english but customer wanted to have text in spanish, tried to change .mo file and it worked but i could not get to my control panel, deleted wp from server and re-installed in spanish, install goes right until it tell me that database already exists i need to erase it before conitnuing, i have changed my datbase 3 times different names and same answer. it does install but very unstable and crashes (goes to white screen) every time i try to install mantra theme

any suggestions please!!