Cannot send emails using Windows Live Mail 2011

There are a number of misunderstandings in your post. Let's look at them one at a time:

the emails to be sent are in the "Sent Items" folder.

No - email to be sent is in the outbox. Only mail which has already been sent will be in the Sent items folder.

When I went to another WiFi location I could send and receive emails ... I have spoken to my ISP provider who says it is not there problem.

When you connect from another WiFi location, you're probably using a different ISP. This may or may not affect your ability to send, depending on which SMTP server you're trying to access.
 

Sometimes when I try to send I get a message from Windows Live Mail "The spell check on this document was halted. Do you want to send anyway". 

This has nothing to do with your ability to send messages. It's a bug. To avoid seeing this error message, when viewing your message list press Ctrl-Shift-O for Options. On the Spelling tab, deselect Always check spelling before sending and select Check my spelling as I type.

I have tried changing the  Outgoing mail smtp from 25 to 587 with no effect.

Each mail server has its own settings, so what works for one won't necessarily work for another.

Whenever Windows Live Mail fails to send a message, it will display an error message. This gives clues to what's wrong, so it's the key to troubleshooting. Click on the error message to select it, then use right-click to copy it and paste it into your reply.

Hello,

Thank you for your post. I understand that you are unable to send emails using Windows Live Mail. It is most likely that this is due to Windows Live Mail related files that became corrupted. We would like you to repair the program to fix the issue.

1.       Click Start and on the Search box, type AppWiz.cpl and then Enter.

2.       Select Windows Essentials 2011, click Uninstall/Change.

3.       Click Repair all Windows Essentials Programs.

If the issue still persists, can you provide us the build version of your Windows Live Mail and provide us the exact error message that you've encountered.

Regards.