Many people (and most of those who read these articles) have more than one computer. After a while, some of us even forget what computers we have. I know I do - my memory escapes me sometimes. So what can we do?
The most obvious answer is to make a list. But what if you forget to update the list?
So the next answer is to let your computer track your computers. If you can find one computer (and if you can't, your problem exceeds the scope of PChuck's Network for help), you can run one of these free utilities, and find the others.
Angry IP Scanner, and SoftPerfect Network Scanner, provide quick, one time IP scans of the local network, and give you a neat tabulation of all addressable devices, that respond to pings, on that network.
The Dude, on the other hand, will do an auto discovery scan of any subnet of interest, using multiple protocols - IMAP4, IP, and SNMP. And it will monitor connectivity, on an ongoing basis, of all discovered (or manually defined) devices, using those protocols and more - DNS, HTTP, IMAP4, IP, and NetBIOS. If you're tired of checking your server every couple of hours, to see if it's up, use The Dude, with its customisable polling intervals, to watch your server for you, and notify you when it doesn't respond to polling on any relevant protocol.
Maybe a couple of years ago, you would use tools like these at work, and pay well for them. These tools are free, and your home network can probably benefit from their use.
All three of these tools have a permanent place in my toolbox.