as PirateEric says, make the above workflow for checking after 14 days if the comments field has been filled, if it has been, no email will be sent to remind them, this means you can have a separate workflow for when the comment field is filled:
- I created a field in my list, named "creatorEmailSent" this ensures that the email is only sent once.
- Create workflow and check "Start Workflow automatically when an item is changed", this will then start when an item is changed.
- Next step is to check comments has been changed, "wait for comments to equal not null" or "If comments is not null"
- Next Step would be to check that now the comments value is not null, has the email already been sent, "If creatorEmailSent equals False"
- Next step is to send the email, "Email these users" and select the creator from the "Workflow lookup a user" and Current Item.
- Set the creatorEmailSent to True.
To set the comments as the body of the email, within the email click "Add or Change Lookup", select Current Item, Comments and As String from the 3 drop down boxes.
Addition for wait 14 days email:
- Again as a check add a field, "assignedToEmailSent" to avoid possibly sending the email twice.
- Create a List workflow and check "Start Workflow automatically when an item is created", this will then start when an item is created.
- Next step is to set the work flow to pause for 14 days "Pause for 14 days, 0 hours, 0 minutes". This will then stop for 14 days and restart on the specified date, it will then complete any processes below.
- Next Step would be to check if the comments value is still null following the 14 day wait, "If comments is empty" also check here that the email hasn't already been sent (see above workflow for how).
- Within this if, you now send the email, "Email these users" and
select the appropriate person "AssignedTo" from the "Workflow lookup
a user" and Current Item.
- Get the assignedToEmailSent to True.
To summarise the process above, when your item is created the workflow starts, it instantly sets to wait for 14 days, following this 14 day period it wakes up, checks if it matches the criteria to send the email, and sends it if required.