Well, if it wasn't totally dead when it stopped being accessible a few thousand power on/off cycles may have finished it off, especially if there was something mechanical, such as a head crash.
For the following I have to make a few assumptions, since the exact procedures would depend on a few things. The disk in question may have been the computer's system disk, which would mean that the computer was not working for these seven years. Or it was an additional disk, in which case the computer would be working, but the drive letter for this disk failed to appear. Or, the drive letter is there but the disk show as empty or an error is displayed when you try to access it.
So, in any event, here is what I would do:
Either in its current computer or connected to another one (by whatever means, from a native SATA or IDE connection to a USB converter) , try powering it up and listen to any noises it makes. Does it keep spinning without any "unhealthy" noises? If not consider a data recovery service and the cost thereof in relationship with the value of your data.
If it seems to spin okay have a look at what the disk management console of the system has to say about it and if it has been given a drive letter. Will it accept a drive letter assigned manually if it didn't pick one up automatically?
Depending on the findings at this point there may be different things you can try.
Ideally, there is a drive letter and you can look at the contents of the drive using the Windows explorer.
There might have been a suggestion that you need to format the disk before you can use it - DONT!!! - Formatting is a fairly efficient way of throwing away any data on that drive, regardless of whether you can read it yet or not. At this point most of us would have to get in knowledgeable help - is there an old or incompatible file system on the drive? Is there maybe a file system error that can be fixed? If you aren't experienced enough to figure this out, now is the time to get help. The data recovery service is an option, but they are costly if they are any good. Up to a point the techie at your friendly computer store or the nerd next door may be sufficiently skilled for this, but make sure that between them and you you know their limitations and when to stop!
One thing I have done in such situations in the past is to create a sector by sector copy of the disk without any regard to the file system structures and then only work on the copy. In one case I actually copied everything except some unreadable sectors. By patching some of the FAT sectors manually I managed to get the file system (FAT16 at the time) to hobble along for the time being and then to recover lots of the files pointed to by the directories I found. It was critical that the drive (a copy) was read-only while recovering. There is no telling what Windows (or Linux) would do trying to repair file system inconsistencies it discovers.
I doubt if I could repeat that stunt today with an NTFS drive ... fortunately Windows itself can often patch things up reasonably well.
These last two paragraphs are here to scare you enough to make sure you don't try anything fancy with your original data if you aren't 120% sure of yourself. Rather find someone that knows what s/he is doing. And be prepared to pay for professional help, assuming that the data recovered is worth it.
I purposely left some items at a fairly high level. First of all this post could get very big otherwise. And then, I don't know how much you can already do. It is usually better to take you there step by step. And lastly, you left your original posting very short. So there is lots more you can tell us here now that you have been given a few initial hints.