Yes. There are time portals controlled by Mystra, and one heck of rare 9th level spell to take you there.
Edition notice: Most of the stuff below is from AD&D 2nd sourcebooks. The question does not ask for a specific edition (fluff only) so the content below should be adapted for other editions. Not hard, as the effects do not change game statistics.
The deity of Time in Forgotten Realms (Faerunian pantheon) is Mystra. It is a rather unknown piece of her portfolio, because she really dislikes time travel. This is discussed more in depth in the Chronomancer supplement for AD&D 2nd. Chronomancers are shunned in the Realms, and quickly invited to leave for other Prime Material crystal spheres.
Nevertheless, time travel do exist, in a controlled fashion.
In the Arcane Age supplements for AD&D 2nd, there are mentions of time portals and the time conduit spell, that can take adventurers back in time. One of the plot hooks for Netheril and Cormanthor sourcebooks is to take an adventuring party for a hike back in time.
There are time gates on Faerûn, but their locations remain a mystery. Ancient texts of Mystryl's faith talk of three gates that were created either through accidents or great fortune. Unknown to any other races on Toril, there is one other time gate, and that is known only to the High Mages of the elves. The time gates are older constructs than anything else in the Realms, either ARCANE AGE or modern time periods. They predate the first dwarven realm on Faerûn, and even the elves seem in awe of their age and power.
Cormanthyr: Empire of the Elves, page 6
The same book describes the Time Conduit spell (the time portals work just like the spell):
9th level spell: Time Conduit
It should be an epic quest to obtain a copy of this spell. This quest should be done with the blessings of both Mystra and Azuth, and the spell should be used with great caution, else the mage draws the wrath of the deities that control magic itself.
The important points in both forms of time travel are:
The trips are always for a 1-year period. Characters arrive on the early minutes of the first day of the year (1 Hammer) and the conduit brings them back in the night of the last day of the same year (30 Nightall).
All prepared spells, spell slots and psionic power points are stripped from the characters. They need to rest to prepare again their spells / recover their powers.
All spells that do not exist at the epoch of arrival are removed from scrolls and spellbooks. Those are otherwise unaffected. For sorcerers (or spontaneous casters) it would be wise to do the same, temporarily stripping the knowledge of the forbidden spells.
All equipment and items that are not yet invented are removed as well.
Upon return, those equipment and spells (that were removed when going) are returned to their original places. The spellbook will be as it was before entering the conduit/portal.
Most items and spells learned while in the past may be removed by the conduit. Those are forever lost in the timestream.
A whole month (30 days) will have passed (in their normal time-frame) when the characters return.
One cannot go back in time to a epoch where one already existed. You cannot visit yourself. You cannot return twice to the same year.
Time paradoxes are resolved with great prejudice to the one that caused it. This is not an issue when visiting ancient times, as history can rewrite itself over the centuries. But some idiot that decides to become his own grandpa will be erased from the timestream.
If the characters traveled using a time gate, the gate will either move to another location, or the knowledge of the gate location will be removed. One must quest again to find this gate (or one of the others). The spell Time Conduit is not lost or forgotten, but using it repeatedly is a surefire way to earn a visit from Mystra's servants.
I recommend reading Cormanthyr and Chronomancer supplements.
As for psionics, there is the Time Travel psychoportive science. It is described in The Will and The Way Dark Sun supplement (but is available for psionicists everywhere).