"I know there is No Planet X but if there was would we be able to see it by now with a telescope or not really."

I believe term Planet X was a term used before Pluto was discovered- so in a sense Planet X has already been found- the Planet Pluto. But some have used "Planet X" to mean another (or next) planet to be found [in our solar system]. If this is what is meant by Planet X, then I would say it is very likely that one or more Planet X (s) will be found. [To add some unnecessary complication; there is some debate over when objects are properly called planets- at what size (or characterization) does a large "minor planet" {asteriods such as NEOs & KBOs (Near Earth Objects & Kuiper Belt Objects, respectively)} become a planet. It "could" be said that Pluto borders on being a planet and/or a Large KBO].
Planet X could be a KBO which is discovered in the future which is around the same size or bigger than Pluto.
And/or Planet X could be a planet beyond the Kuiper belt (say at twice the distance or more). This leads to the question of "would we be able to see it". With our current telescope capablity if you knew exactly where this object was in the sky you could detect it as a point of light (though it might be quite dim (because it is far away or because it's surface does not reflect light well {or both}). At the resolution required to see such distant objects the sky is very large and filled with hundred of billions of stars and galaxies- making finding a needle in a haystack seem a simple, quick task. Another aspect is that the large telescopes aren't spend much time looking for Planet X- there are spending their time looking at far more distant objects. So the question is finding it more than being able to see it. The search for NEOs which could impact Earth also finds KBOs and other objects. And there programs which though doing something else could stumble across a discovery of a "Planet X".

Perhaps all the above is not what you mean by Planet X, perhaps you are concerned about some gaint planet which has a trajectory like a comet. All I can really say about that is there is a lack of evidence which supports this possiblity. Though there certainly should be larger comets than what we have seen in the short time we have had the technology to allow us to know what these objects actually are.