I recently had an incident where I had to reinstall WSUS on my SCCM server, and in the process my PXE boot stopped working. I would receive the following error when trying to boot from PXE:
PXE-T01: File not found
PXE-E3B: TFTP Error – File Not Found
This is a fairly common problem, and usually removing and reinstalling the PXE service point will resolve the issue. Reinstalling or restarting the WDS service is also a possible solution. I also usually run the PXE.msi install package located in bini386 in my ConfigMgr installation folder to properly integrate it with WDS.
In my case I tried all of the above, but to no avail. It turned out the boot files for PXE had disappeared from my RemoteInstallSMSBoot folder, and all I had to do was to copy the files from RemoteInstallBoot into their respective folders. After this my machines started booting from PXE.