accidentally formatted all three drives, cant reinstall windows

As you have a dell system, you could try contacting them directly and asking about a set of recovery disks. Dell always used to be able to provide these which will boot up and put your system exactly back as it was when shipped. They may charge a nominal handling fee for the disks but they could be the only sure way to get the system back with its recovery partition and system/data setup

Trentongm,

Barman has given you some excellent advice.

Dell's support in this area is exceptional.
Now let me dig up the link you need.
https://support.dell.com/support/top.../backupcd_form

Lost your Windows discs? How to get replacement media, legally | ZDNet

Welcome to SF! trentongm

Can I ask what type of 7 disk you used for the new install? You apparently installed 7 onto the factory hidden recovery partition often seen at the front end of the drive unlike other brands where that is seen at the back end instead as the Windows installer will generally look for the first primary type partition.

I think we can all agree obtaining a set of recovery disks or disk for shipping costs only being a customer is the first best option. If however the disk you have there is a retail disk of the exact same edition and 32bit or 64bit Windows as the system came with you would simply enter the product key found on the sticker attacked to the back of a desktop or bottom of the laptop there to see Windows activated.

What that means if the pc came with the 32bit 7 Home Premium you would need a 32bit 7 HP retail disk to replace the loss there and leave the prepackaged softwares bundled out. The device drivers for chipset, video, onboard sound if no separate expansion card would all need to be downloaded separately of course from the Dell support site or other.

The Dells generally come with an option at post time for seeing a full restoration however by pressing a key combination without the need for a recovery disk. Unfortunately only the recovery partition was lost during the bad install you saw there where now simply wiping the drive clean for one single primary for 7 would be a thought to consider.

The wipe of the drive would mean the hidden recovery partition is removed recovering that drive space as well as the option for allowing the 7 installer to create a new 100mb System Reserved boot partition in it's place or creating the single primary ahead of time. Before deciding however you will want to review the guide on how to perform a clean install of 7 seen at Clean Install Windows 7

You will want to get familiar with the steps for installing W7 regardless of which option for getting 7 back on you decide to go with.

Everything you need to Clean Reinstall - Factory OEM Windows 7 with the Product Key on COA sticker is in the blue link.

The error you are getting "Bootmgr is missing" is because it's attempting to boot the HD which has been deleted so there is nothing to boot. You must boot the DVD by setting it first to boot in BIOS or tapping at boot the Dell F12 one-time BIOS Boot Menu key.

I would unplug all other HD's except the one you want to install upon, follow the steps in tutorial to delete all partitions, then click Next for the installer to create and format the install partition and begin install.

trenton,
The install disc is from Microsoft, from Dell or from where?

If the the install disc is a disc you made using a Dell option, can you tell us what that option was.