Who is your ISP? Who has been managing the router and network?
Basically your reset has returned the router to its' factory settings. You must start completely over with respect to restoring your network and regaining internet access.
First you must reconfigure the router.
Use a browser and the router's default IP address: 192.168.0.1 to gain access to the router.
Then you need to login into the router using the admin login name and password to access the router's administrative functions.
Login name and admin can vary. Here is a link to possible choices:
https://www.cleancss.com/router-default/D-Link/DIR-600
Then you must reconfigure the router per any instructions provided by your ISP along with the User Guide/Manual for the router.
Found the following link:
https://www.router-reset.com/reset-manuals/D-Link/DIR-600-rev-B1B2
Read everything and plan out what steps must be done and the necessary configuration settings for your network.