Upgrade any DOS based System, specially developed in COBOL into Online without changing Input Screens and reports?

I don't know if I understand your question correctly . But if you want to use the same COBOl  program online without changing any thing . That is only possible if you have VPN or a remote access on a machine where this program install . If you want to convert the program to make it support web and the new technology my advice to you to convert your program from COBOL to C# or Java .If you don't have expertise in both COBOL and C# OR Java you can use one of the converting program and tools to convert from COBOL to C# OR Java and they are trusted and very helpful in you case .

I hope I helped you by this answer .