Html encode decode in asp.net store and fetch

Question

I have a problem with restricting malicious content in a field which can accept any input from the user.

I have to encode that field and save it in the database - see examples:

1st example

<space> is saved as <space>

2nd example (malicious text)

"><svg/onload=prompt(1)> is saved as "><svg/onload=prompt(1)>

Now in reports I have to decode that into actual text, but the second text is malicious script now. What should I do?

Is there any other way to stop malicious text on both client and server side?