Network not comunicating internet, need help

[QChoumont]

I just started a new job out of college as IT, and today was my first day. The internet went down last friday and I cant figure out how to get it back up.

We have a Cisco router that outputs to a D-link switch. This switch is connected to our domain controller an application server and a couple of server room computers, These computers have internet access.
The D-link switch has 16 ports about 12 are being used 1 - application server, 2 - DC, 3 - My IT computer, 4 - Goes to the switch room in the basement, the rest are used for VOIP and security

The Cable that goes to the switch room connects to an HP 1800-24 which splits into 2 other HP 1800-24s and a couple patch panels. 

I cant seem to get the internet to propagate these switches. I've talked to the previous IT guy and He suggested I reboot the Cisco router and the HP switches and just let the routing tables do their thing but that didn't work.
I'm currently trying to map out the network and figure it out but I don't really know what to do.

Any suggestions?
All computers have network connection to connect to the Domain Controller but the Network storage isn't accessible.
I can only connect to 1 switches web portal when I wire my laptop to it, the other 2 don't give my anything.

[Sir Asvald]

What Cisco router is it? is it a enterprise router? SMB router? How are you getting internet? Fiber connecting the router??

[QChoumont]

On 6/8/2021 at 2:10 AM, Sir Asvald said:

What Cisco router is it? is it a enterprise router? SMB router? How are you getting internet? Fiber connecting the router??

Thanks for offering help, it turns out that 2 of the HP switches died the weekend before I started work. Twas a bad time.