Need L511Z ISO "Boot & Recover" CD

@CnTx  If your system has a factory image Recovery partition, then you don't need a disc to boot into that.  You should be able to press a specific key combination to activate that.  The whole point of that partition is so that you do NOT need anything else to recover your system.  If you're booting from a disc, then you'd be installing an OS from that disc.  But if you do NOT still have that factory Recovery partition, then that's what you'd have to do anyway.

But if you're ultimately planning to go to Windows 10, then just start the upgrade from within Windows without dealing with drivers.  You shouldn't actually need to install all of the Windows 7 drivers for your system before starting the Windows 10 upgrade, and most of them will get replaced or removed as part of the upgrade anyway because not all Win7 drivers work for Windows 10.  In fact technically you can just perform a clean install of Win10 and try to activate it with your Win7 product key, and you can still burn Windows 10 install media onto a DVD.

Note however that regardless of whether you upgrade from an actual Windows 7 installation or perform a clean install of Win10, it's unclear whether Microsoft will give you a free upgrade at this stage.  Some people are still having success, but the official policy is that the free upgrade period ended a while ago.  But if it's going to work, it should work even if you perform a clean install, again by entering your Win7 key into Win10.  And if it doesn't work, then it wouldn't have worked even if you jumped through hoops trying to perform an in-place upgrade.

The only part that's a bit confusing to me here is that you say no Windows 7 drivers are available from Dell.  If the system came with Windows 7, then drivers would be available on support.dell.com.  If you can't find Windows 7 drivers because that system originally shipped with an even older OS like Vista or XP, then there's no point at all trying to install that OS before moving to Windows 10 because there is no in-place upgrade path to Windows 10 from those older OSes, and no free upgrade either.  So if you want Windows 10, you should just perform a clean install and then purchase a license through the Microsoft Store afterward (or purchase a key through retail outlets if you can find a good deal through some online vendor.)