If you are getting an access denied message when starting the DHCP client servce, this is most likely because the permission got changed. Some programs then to do this. e.g. third party firewall application

In order to add back the permissions, you will need to open your Registry editor program.

– Click on “Start” and then “Run”
– Type in “regedit” and press enter
– Browse to the following folders

\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dhcp\
\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\

– Right click and choose “Permissions” to add permissions
– Add the Local or Network service account
– Give it “Full Control” rights
– Go to the DHCP Client Service under Services
– Double check and make sure the Logon user is using the correct username. In this case, it should be local or network service.
– Restart the DHCP Client Service

Also, double-check all of its dependenices services and make sure that it is also started. Otherwise, DHCP might still not work.