UPDATE: THIS TWEAK WILL NOT WORK WITH THE NEW BLOGGER REPLY COMMENT SYSTEM. CLICK ON 'REVERT WIDGET TEMPLATES TO DEFAULT' TO UNDER THIS TWEAK.
Quick Note: This tutorial doesn't teach how you can bring back your missing comment form - as it is highly likely that it is a problem with your browser. This tutorial teaches you how you can add a back-up link to allow your readers leave a comment in case your comment form doesn't appear in your readers' browsers.
The Blogger Comment system is an important part of any blog. Blogger gives you the option to either place the comment form embedded in your post page (known as 'Embedded below post'), or have the comment form in an external page. The external form placement comes in two different options - to load the external comment form from the current page (known as 'Full Page'), or pop-up a new window to load the external comment form (known as 'Pop-up window'). At any given time, you can only choose either one of the two options provided (either embedded or external placement).
Lot's of users prefer to have the comment form embedded within their post page because it is so convenient for readers to leave comments within the page itself. Besides, the external form placements have their own disadvantages when it is seen holistically. Full Page placement will overwrite 'over-load' the post page to open the comment page, and Pop-up Window placement will open a pop-up window, which will get blocked if pop-up blockers are installed at the reader's side.
Here comes the problem. Embedded comment forms are not foolproof either. Due to some browser problems, and/or add-on related issues, sometimes the embedded comment form becomes dysfunctional. I have experienced this at two different times, and until today, I could not identify what caused the problem. It just resolved by itself. But during that period, I could not leave any comments anywhere. This could happen to you too. You could lose lots of comments if your readers' browsers fail to make the embedded comment forms functional - and you'd be so clueless when it happens as usually it is not epidemic.
Solution: Place both embedded comment form and external comment form together. Embedded comment form as primary option as usual, and a link to external comment form as a back up! I spent lots of time to come up with this one, and I guarantee you, this is first on net!