Hi @Barath_Alagarsamy. Welcome to the forum.
That is not much information to go by. What type of help are you expecting or hoping for? Which version/year of Inventor are you using. Are you wanting to try to do this entirely by code, or entirely manually, or by code but with some manual interaction involved? No one will be able to provide a complete working code example without knowing all the details involved, because we do not have your set of files, or your TitleBlockDefinition, and do not know which custom iProperties are involved. At the innermost part of a code process like this is the Inventor.TextBox object, and its TextBox.FormattedText Property value. This is different from the TextBox.Text Property, because when 'Linked' iProperties, Parameters, and such are involved, the FormattedText Property's value will pretty much always contain some 'XML Tags', which can be complicated to understand, so can be even more complex to properly edit. The only online Inventor API help we have for that is the XML Tags for FormattedText page, which is nice, but does not provide much as far as working code examples. What I usually recommend to most folks planning on editing some FormattedText is to use some form of feedback to write the current value of that Property out to the iLogic Log screen, or as the default value of an InputBox, or at least a MsgBox, so you can see the code it currently contains. Then maybe change something about it manually, using the 'Format Text' dialog. Then get the value of its FormattedText again, to see how what you did manually changed the code it contains.
Wesley Crihfield

(Not an Autodesk Employee)