How can I install a HP photosmart 7520 when I do not have a disk?

https://h30434.www3.hp.com/t5/Printer-Software-and-Drivers/Photosmart-7520-touch-screen/td-p/6479867

Try reinstalling the device driver.

You can find the device driver here: HP Photosmart 7520 All in One Printer Software and Drivers

I’m happy to help further over the phone at https://www.6ya.com/expert/james_d4449ffdf318a2c3

www.ask.com/
www.wikipedia.org/
www.infolinks.com/
/mfg.name/make/model/installation/instructions/ink/cartridges/installation/

some times there are parts that come off the old printer and install it on the new ink cartridges, ( 2 peice unit)
look in the box of the ink cartridge for instructions, the cartridges are the ink portion not the drum portion drum round looks like sceran wrap roller, it may have to thin peices of wire, be careful not to brake wire.

www.toutube.com/hp/photosmart/printer/cartridge/installations/

Try removing the printhead and cleaning the contacts on the printhead. To remove the printhead, see this video instructions:

I have setup HP printers with both connections with no trouble even though their manual said to disconnect usb after wireless setup. I don't know if this would work with every model. I am including a link to the manual pdf for this model and a link to an HP employee discussing this on a different model. I would just try it.

Manual
http://www.hp.com/ctg/Manual/c03456524.pdf

HP Support
Re Can use both USB Wireless connections on OfficeJet 6700

Does it grab paper at all? Does the paper jam in the doc feeder? does it scan when place on the glass?

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

You will have to check the equipment driver itself. While attempting to print, try changing the page size (go to page setup). This will give you an idea.

You may download the manual and more from HP Photosmart 7520 All in One Printer User guides

You may download the manual and more from HP Photosmart 7520 All in One Printer User guides