Hi, The space character should look like " ", you just typed it as "". Try to keep a space character in between the double quotes 

fn-Replace(fn-GetQueryString(mNum),"%20","") change to 

fn-Replace(fn-GetQueryString(mNum),"%20"," ")

If it does not work, try below.

fn-Replace(fn-GetQueryString({TextStart}mNum){TextEnd},"%20"," "), more details in this article

Hi, 

Should i replace TextStart and TextEnd with anything, just copy and paste?

I have tried both, still no luck

fn-Replace(fn-GetQueryString({%}mNum){0},"%20"," ")

OR

fn-Replace(fn-GetQueryString({TextStart}mNum){TextEnd},"%20"," ")

No, just copy paste the {TextStart} and {TextEnd} as is, Nintex understands to consider the string in betwen these two words for processing. Please see the article that I mentioned in previous reply.

Hi Team,

Anyone has an idea on this. please.......................

@pfudala Can you please help on this.

@ramanjjilunaidu Try this:

fn-Replace(fn-GetQueryString({TextStart}mNum{TextEnd}),"%20"," ")

@Nunezma tried as it is still no use.

fn-Replace(fn-GetQueryString({TextStart}mNum{TextEnd}),"%20"," ")

result still same => Complete%20write-off%20exercise

Can you try a second calculated field?

First getquerystring and then try removing %20 from Complete%20write-off%20exercise that field and see if it works?
Replace(Text,"%20","")

Or try this:

Replace(fn-GetQueryString({TextStart}mNum{TextEnd}),"%20","")