Previously, the local machine was installed with dotnetnuke2.0.3 for ease of use. Now there is a problem with installing dotnetnuke2.1.2 ..., Please help

Type localhost/dnn and the following message is displayed:
Server Error in '/dnn' application.
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The resource cannot be found.
Description: HTTP 404. The resource you are looking for (or one of its Dependencies)

Cocould have been removed, had its name changed, or is temporarily unavailable. Please

Review the following URL and make sure that it is spelled correctly.

Requested URL:/dnn
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Type localhost/dnn/default. aspx. the homepage of dnn 2.1.2 appears, but the image is not displayed and the *. CSS style is not supported.
Function. After logging in with Admin or host, the admin or host tab cannot connect to the corresponding page.