What do I do if I mistakenly deleted crucial drivers while trying to reinstal windows 7 from laptop

Hey I bought a Dell Latitude e6510 laptop a few months ago for work, well since then I don't work at my old job and I decided to to sell my laptop. Well I could not find any info on factory reset other than without the software which came with it, that is a problem because i bought it off craigslist. Well I finally decided to do the normal thing and just reinstall, but i mistakenly deleted the files on partisan 0 which is the laptop's only hard drive. This partisan is what I'm guessing all of its drivers are on as well as the windows software, so now when I try and reinstall windows im getting an error saying crucial files not found. I found the drivers on dell's website, now I need to install them. How do I do this because I've never done this way on a laptop before in this fashion. Do I download this into an iso like dell offers and then mount it as boot on a flash drive, then boot from it to install? Please help I was planning to sell it tomorrow and goofed.

If you have the a Windows ISO that matches the OS that came with the laptop, get the ISO and try to install from that.

Afterwards you should be able to install the drivers without any issues from here: http://www.dell.com/support/home/us/en/19/product-support/product/latitude-e6510/drivers/advanced