Problem customized rom installations. Need help.

Hi! I have a problem in my phone. please somebody help. In my rooted Walton primo ef3 I had been using an app named romtoolbox. I used this app to change my bootanimation bootsound and to browse system apps. But I am not an Android expert. In that app there was an option called Rom installer. I didn’t know how that worked. I clicked inside found something that told me to select .IMG file in two place (boot and recovery). But I didn’t know what was .IMG file.I thought it may be an image file. So I selected a .jpeg picture and pressed install. Then I tried to reboot my phone but is not turning on. It just showes the white screen written primo ef3 powered by Android that used to come earlier during turning on my phone. And the screen remains like this untill my battery emptied. Same thing happens if I connect charger after switching off the phone by pulling out the battery. Now how can I solve this problem?