Sharepoint 2013 server Word Documents and PDF Documents not Opening in Custom List Attachments?

Question

I was uploading documents to sharepoint custom list.The file will save in Attachement COlumn.But when i try to open Pdf it shows failed to open PDF.When i try to open Word document it shows we are sorry we found problem with its content.

How can i open PDF and Word Documents in My sharepoint 2013 server.

I tried to activate this feature(Open Documents in Client Applications by Default) But still the documents Are not Opening ?

Error Messages :

When i was click the Link Report(!).pdf i was getting following error.

For word Document i was getting following error.

Answer 1

Your files really look damaged/corrupted. Maybe something on the line does edit/replace their binary content.
For instance, don't you have a proxy along the line that may intercept the files and change them on the fly?
Or custom code (such as an HTTP Handler) deployed on the server?

Can you download the file (not open) on your disk: thencheck its size, and open it in Notepad to see how the actual content looks like.

[EDIT]
After you posted the code you use to upload attachments, the problem becomes clear: you wrongly upload the files. You never get the source file content to inject it to the target. This obviously results in files with the correct size but that are absolutely empty.
The correct code would look like (one line to replace the entire code block you posted):

oListItem.Attachments.Add(oDocItem.File.Name, oDocItem.File.OpenBinary());