WHM Login always incorrect password need to reboot vps to be able to login

In my experience you are probably being locked out, due to brute force login attempts from unknowns. Potential hackers.
Find cphulk and add your ip or range of ip's (if dynamic) to the white list for a start.
Range of ip's will go along the lines xxx.xxx.0.0/16.

Consider using host access control.
Allow access to all for your ip (or range of ip's), this one goes along the lines xxx.xxx.0.0/255.255.0.0

All - IP or Range - Allow

And deny all to everyone else until you have it secured at least

All - All - DENY

Then as a matter of immediate importance, install CSF (firewall).
When CSF is installed, choose a pre-configured profile as a starting point (i chose high).
And remember to take csf out of test mode.

It's not difficult but can be quite daunting when your'e first starting out.

When you've done all this, come back as the guys on here are really helpful.

 

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cPHulk Brute Force Protection

 

Install csf from a root login.
http://download.configserver.com/csf/install.txt

Leave CPHulk in tact, just add your IP or range, and any others that you trust, ie your VPS provider.

Also under security center, add your entries in Host Access Control, like thus.
Allow access to all for your ip (or range of ip's), IP entries should look like this for a range 111.222.0.0/255.255.0.0

All - 111.222.0.0/255.255.0.0 - Allow
Also add your VPS provider and anyone else you trust, eg your work ip, your home ip.

And deny all to everyone else until you have it secured at least

All - All - DENY

The Deny rule should always be the last entry apparently, so if you add any more entries, make sure the denies are at the bottom of the list.

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One other thing, finding your way around WHM and it's many features can be tricky at first, knowing for example where CPHULK is.
Using the search box (top left), will help find these things.

 

Now might be a good idea to run a quick security scan, and see what you can or dare tighten up.
If you installed CSF, you might want to consider a CSF security scan also.

CSF also gives very easy access to the logs, you'll be shocked as to how many devious goings on there are behind your back