This looks like more of a database install problem than a GIS issue. For that reason, a quick search on our sister Stackexchange site StackOverflow, turned up this question and series of answers:

Postgres could not load library unknown error 14001

Here is the answer that did the trick: http://stackoverflow.com/a/13513473/1388679

It boils down to an install on a Windows machine that is missing the correct version of Microsoft Visual C++. Since you have not provided that information, this is a bit of a guess, but it seems to match what you are running into.

One other solution also mentioned on that thread would be:

1. Completely uninstall Postgresql and all of its dependencies.
2. Make sure that all Windows updates are applied correctly.
3. Reinstall Postgresql and PostGIS. This would ensure that the correct supporting files are being installed with the database.

This looks like more of a database install problem than a GIS issue. For that reason, a quick search on our sister Stackexchange site StackOverflow, turned up this question and series of answers:

Postgres could not load library unknown error 14001

Here is the answer that did the trick: https://stackoverflow.com/a/13513473/1388679

It boils down to an install on a Windows machine that is missing the correct version of Microsoft Visual C++. Since you have not provided that information, this is a bit of a guess, but it seems to match what you are running into.

One other solution also mentioned on that thread would be:

1. Completely uninstall Postgresql and all of its dependencies.
2. Make sure that all Windows updates are applied correctly.
3. Reinstall Postgresql and PostGIS. This would ensure that the correct supporting files are being installed with the database.