Hi,
What kind of disk you have?
for non hot swapable non root disk follow the procedures below:
Let us assume that the disk /dev/dsk/c1t1d0 has to be replaced. This disk belongs to the data volume group vg01.
1. Replace the failed disk.
2. Boot your system into multi user mode as usual.
3. Use the vgcfgrestore command to restore the LVM configuration data from a configuration backup file to the physical volume:
# vgcfgrestore -n vg01 /dev/rdsk/c1t1d0
4. Activate the volume group for including any physical volumes that were previously listed as missing:
# vgchange -a y vg01
5. The vgsync command synchronizes the physical extents of each mirrored logical volume in the volume group. Synchronization occurs only on the physical extents that are stale mirrors of the original logical extent.
# vgsync vg01
NOTE: The synchronization process can be time consuming, depending on the hardware characteristics and the amount of data.
6. Check successful completion by
# pvdisplay -v /dev/dsk/c1t1d0
which should not show up any stale extents and finally by
# vgdisplay -v vg01
Did you take a backup?