Phone numbers displaying as scientific notation no matter what format selected

I'm working with a sheet of contact details and very, very annoyingly, the column of phone numbers has some values messed up.

My numbers are generally 01XXXXXX , or 08XXXXXXX , or if 353XXXXXXXXX

Excel converts the 01XXXXX numbers to 1XXXXXX and the 353XXXXXXXXXX numbers it displays in some scientific notation.

I've tried changing the format of the column to both text (hoping that it would restore my leading zeros and special (mobile phone - Ireland), but that doesn't help.

In one of the cells where a number has been converted to scientific notation, the number is shown as 3.53XXXE+XX, but if I select the cell, the correct number is shown in the bar at the top of the sheet (dunno what it's called).

Some other threads here mentioned changing the fixed decimal, but that doesn't seem to have helped me.

What else can I try, please?

its got to be text, format cells before you put data in
or select column with numbers
data /text to columns
click next
click next again
in the column data format click the text button
click finish
when thats done come back and we'll sort the missing 0
probably =IF(LEFT(A1,1)="1","0"&A1,A1)

That worked a treat, thanks so much.

So now, I have all the numbers displayed as they were put in, except some of them don't have leading zeros.

Instead of replacing the leading zeros, I could just put a +353 in front of all the numbers that don't have one already.

Appreciate it if you could point me toward instructions on that!

Sorry it to so long for me to reply, I didn't know anyone had answered. (must check my notification settings)

got an example? please attach with required result shown