Error Report: 503 Service Unavailable

Hi Members,

I have recently tried to modify the logon screen on my portals but unfortunately I was got struck. I have changed the files

1.com.sap.runtime.logon.par(in portal file system)

2.authschemes.xml(in visual administrator).

Now the problem is My portal Login page doesn't appear ,instread it throws the below error

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503 Service Unavailable

Servlet [prt] will be unavailable for undefined time.

Details: javax.servlet.UnavailableException: Initialization of Dispatcher failed

Exception id: [0016D30FFBDC006D0000002B00000F2000044318BC74F863]

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Even I tried with restoring the above 2 files but I found no change.

Is there any way to restore the portal page again?

Thanks for your Reply and Appriciate the time.