All of a sudden, I can't open links in my emails. Not just yahoo, but others as well.

For the last 2 or 3 weeks, I haven't been able to open links in my emails. This includes personal & business accounts. One is Yahoo & the other is Outlook Exchange. I've never had any problem before. It's only on the IPad. I have 2 other tablets not IPads, a Samsung smartphone, & I have no problem on them. I can't think of anything I've changed that would cause the problem. Does anyone have any ideas as to what the problem is and how I can fix it?