The easiest way, without regex:
Select the bloc you wanna replace and press Ctrl+H. Npp fills the Find what box automatically, with the proper codes inserted (although invisible, unless you try Find in files first; the results panel will show the Find string with the \r\n codes inserted properly).
Select the text to Replace with. Unfortunately, Notepad++ does NOT fill the box with the proper codes automatically. You need insert the \r\n codes at the end of each line manually.
some text**\r\n**
some other text**\r\n**
Comments**\r\n**
Comments**\r\n**
\r\n
(Value 1<)\r\n
Go to the end of each line and press Delete (it deletes the EOL codes, LF or CRLF).
It is a one line bloc now. Select the new bloc of text and paste it into the Replace with box:some text**\r\nsome other text\r\nComments\r\nComments\r\n****\r\n***(Value 1<)*\r\n
Voilà!