Unable to launch old OS after installing a new one(dualboot)

Just before I write this post,I launched the WinRe 3 more times.The first attempt and second attempt showed the same results.But after the second attempt,it reported that Windows cannot fix this automatically,OS loader not found.After the three attempts and I again tried to get into it and the winload.exe issue is there.
Then I jumped into G,system32 and looked for winload.exe.There are two files there.winload.exe and winload1.exe. winload.exe is 578 KB in size and the other one 590.I don't know how this happened.Maybe I can fix that winload.exe corrupt issue by renaming the 590KB file as winload.exe?I tried to do it but it says I need permission from Administrator.So I launched command prompt and activated the Administrator account.But I still cant make changes to that file.Please tell me if you know any ways to do that.
Will be doing everything you just said shortly.I haven't done a backup yet.I think if things go wrong,I can still do a clean install of my new OS as I have nothing precious in that partition :). Is it possible to transfer bookmarks from Firefox by copying the profile?
Thanks for your continuous support.

You cannot fix the winload issue any better than Startup Repair can, as it has all fixes and tests included and will run System File Checker if it is required, is run enough times, and System is not irreparable.

You needed to do the backup before you started changing Active flags as stated repeatedly. However you can go in at any time with DVD Repair console or Repair CD to Copy & Paste - in Windows Recovery Console to external USB drive.

I don't know which Firefox file might hold your profile as I back up my Bookmarks, but you can ask Google.

Update:I just reinstalled Windows(the latest one).And it now shows me three options.One of them is Windows7(Recovered).I launched it and startup repair was started and it said that I will need to be logged in as a local user to repair it.So I selected my username and entered the password.The repair process continued and a while later a new dialogue box appeared stating that Windows couldn't fix it automatically.The problem is still that OS loader thing. What do you think about the current situation.Still hopeless?

What happens when you try to boot into the other two choices on Menu? One is C and boots correctly? What happens with the other one?

Again install Easy BCD to C, on Edit OS menu delete each entry and then add G again. Save and reboot.