No display but PC LED’s and fans are on

Hi, for Christmas I decided to get an i7 7700k as a replacement for my i5 6400 as my pc was starting to be slower and I wanted it to speed up. So I took unplugged everything, opened up the case and put in my i7, from here the computer would turn on with LED’s and the fans would come on and the UBS’s would work except from my keyboard and mouse and my monitor which was receiving no display :( I searched the internet for answers and I put my i5 back in and everything worked fine. So on the internet I was told I could fix this by resetting the bios but I had no jumper to put on my pins so instead I took out my cmos battery for roughly 10 minutes and put it back in, before I took it out I had put my i7 back in. After I started up the pc again nothing happened so I put in my i5 again after turning on my pc where the i5 still worked by this time the bios was loaded up first recognising the i5 I had put back in as a ‘new processor’ but this is what I wanted to happen with my i7 so I stupidly shut off my pc without finishing set up or anything else and I put my i7 back in the pc after turning it off and I started trying new things to get it to work such as resetting my components such as my gtx 1070 graphics card and ram. I then unplugged a few wires and plugged them back in but that didn’t work either. I left my pc off overnight, tried it in the morning, nothing happened. I then found out that I should just put in the i5 and update my bios so that it will work with my i7 but after putting my i5 back in the pc agaiiin I turned it on and now it won’t ecen boot up with the i5 in, so now I’m worried I have just ruined my newly upgraded pc. Today I again tried to reseat and replug in some things aswell as holding down my computers off button whilst it was disconnected and I also tried connecting my DVI cable to my Mobo and my gpu aswell as using my working hdmi cable incase the DVI was messed up but NOTHING seemed to work so I have come here in the last hole to try find a solution for this before taking my computer into a store to try have it repaired. Any help is highly appreciated :)