I currently have an index for a blogpost.
The index is a list of all blogs posted with
their dates, title and the url for that specific post,
which i update weekly. the URLs are copied from
the website and pasted into excel.
What has happened lately is that all the past URLs (abt three years worth)
have suddenly become inactive. This means that when I roll over
the URL with my mouse nothing comes up and the I am unable
to open the web page. This requires that I update each URL.
How and why does this happen?
And how do I prevent this from re-occuring?

Any insight and help will be much appreciated.
Thank you.

Motlalepula