The average life of most Time Capsules was about 7-8 years. At that point, both the hard drive and power supply tended to start acting up, so even if we can get the Time Capsule working again, I would not recommend that you use the product as your primary back up device.
Apple does not offer repairs on the Time Capsule.....even if you are willing to pay.....but an independent shop might be able to take care of some simple things. The issue would be cost on any major repairs that might be required.
If you want, we can go through some basic troubleshooting to get an idea of what might be wrong. On the other hand, you might think about retiring the Time Capsule because of its age.
Post back to let us know how you want to proceed.