Can anyone help please!?
Cheers,
A

Do you have them outside in full sun so that they can generate enough energy to produce fruit to maturity? Have you repotted the trees to a larger pot? Sometimes that will cause the tree to put its efforts into producing roots instead of fruit in the near term. If conditions are otherwise satisfactory, after sufficient roots have formed the trees will begin to flower and fruit again. Have you fertilized them with a citrus or other suitable fertilizer?

These are a few ideas to get you started. Others posters should have more ideas. Hope this helps.

Cath

More sun the better--direct, unobstructed sun will help. Outdoor sun is best--many hours of it!. It's normal for some of the flowers and developing fruits to abort and fall off but obviously, there is something not to their liking here--maybe dry interior air. Try to find a sheltered exterior site for them if possible. Go easy on watering and feeding until you see growth. Citrus tend to grow and fruit in spurts. They'll do nothing for months then suddenly sprout new leaves and/or enter a fruiting cycle. Regarding flowering cycles, my oranges, Eureka lemons, and kumquats will bloom in the Spring (earliest, in February) and April is peak (in the Northern Hemisphere obviously). Mine are literally covered in blooms at this time. Fruits seem to spend the rest of the summer maturing and growing but coloring seems to develop over the winter months. Meyer's lemon seems less seasonal and will bloom and fruit throughout the year. Limes too (being VERY tropical) are less seasonal, and given adequate sun and heat, will fruit and flower throughout the year. At least, that's been my experience with Citrus at a non-tropical latitude. Also, Citus and their kumquat relatives thrive on a bit of 'though love'. If you have been watering consistently and keeping them slightly moist, ease up on the water--let them get much drier between watering. Once you see an increase in either green growth or blooming, you can increase watering. Good luck!