Airport Time Capsule Device suddenly "not found" in MacBookPro

Have you tried the basics? Powering off the Time Capsule, restarting your Mac, powering the Time Capsule back up?

What other troubleshooting steps have you performed?

We ask because we don't want to waste your time asking you to do things that you have already done.

As far as resets, you won't lose any data on the Time Capsule hard drive unless you go through a very specific "erase disk" procedure that will ask you at least twice whether or not you really want to erase the hard drive on the Time Capsule.

You seem to be thinking that the issue is with the Time Capsule, but at this point, we do not really know whether the problem might be with your MacBook Pro, the Time Capsule or something else. So, more investigation is needed.

Does the Time Capsule appear if you use AirPort Utility on your iPhone?

If you have not installed AirPort Utility on your iPhone, you can do so by going to the App Store on the Home Screen and entering AirPort Utility in the search box. When you open the AirPort Utility application on the iPhone for the first time, you may be asked for the admin password of the Time Capsule, so you might need to keep that handy.

Obviously, if the Time Capsule appears normally when you perform this check with an iPhone, then you know that the problem is not with the Time Capsule, or your iPhone. The real issue might be with your Mac.

When this type of thing occurs, the only thing that you can do that might help is perform a Hard Reset on the Time Capsule and then set it up again.

To perform a Hard Reset, simply hold the reset button on the back of the Time Capsule in for about 7-8 seconds and release. Then, allow a full minute for the Time Capsule to restart to slow blinking amber light status. The Time Capsule is now ready to be set up again. You can use the same names and password if you wish, or use new names and passwords.

The data on the Time Capsule hard drive will not be affected by the reset.

Time Capsules do tend to start acting up about 5 years of age on average. Not sure whether this might be a factor with your product.

If you find that the Time Capsule "disappears" again in the next few weeks, that is a hint that the Time Capsule power supply is starting to head downhill.